岗哨

The Sentinel
作者：[英] 阿瑟·克拉克 （Arthur Charles Clarke）
译者：邹运旗

当你下一次遥望高挂南天的满月时，千万别忘了仔细观察它的右侧边缘。请你把目光沿着圆盘的弧线向上游移，大概在两点钟方位，你会发现一个小巧的椭圆形黑斑——只要你视力正常，找到它绝对轻而易举。

这是一片群山环绕的大平原，是月球最著名的景观之一，人们称它为“危海”——危难之海。⁽¹⁾译者注：危海是月球上的“月海”之一。早期的月球观察者发现月面有些地区光线较暗，猜测该地区类似地球上的海洋，于是命名为“月海”，同理还有“月湖”“月沼”“月湾”等。反之，其他较亮的地方则被称为“月陆”。实际上，月海是月球上低洼平整的平原，多数为圆形，周围有山脉，大多由小天体撞击形成。下文的“澄海”和“风暴洋”都是月海的名字。危海直径三百英里，四周环绕着一圈巍峨宏伟的山峦，这是一块人类从未考察的处女地。直至1996年夏末，我们才来到这里。

我们的考察队规模庞大，包括两台重型运输机，负责从五百英里外位于澄海的月球主基地运送设备和补给；还有三艘小型火箭飞船用于短途运输，帮助我们越过月球车无法穿行的地带。幸运的是，危海大部分地区十分平坦。这里没有月球表面其他地方常见的危险的大峡谷，就连大大小小的陨石坑和起伏不平的山丘都很少见。我们甚至敢说，强劲的履带式牵引车可以把我们带到任何一处，只要我们想，它就能去，毫无压力。

我是个地质学家——如果认真说，应该是“月球地质学家”——负责领导危海南部地区的勘探小组。我们已经用了一个星期，沿着山脚线的丘陵地带走了一百多英里。十几亿年前，这里曾经是一片古代海洋的海岸线。当时，地球上的生命方才萌芽，这里却已开始步入死亡。海水沿着体量巨大的悬崖侧面退去，落入空荡荡的月心内部。我们刚刚经过的月球大地，就曾经是一片浩瀚的海洋，深度达到800多米，如今却潮汐不再，留下的唯一痕迹是点点白霜，也只在炽热的阳光从未照到的洞穴里才能偶然看见。

月球上的黎明迟缓而漫长，清晨刚刚到来，我们便踏上征程。再过一个地球周的时间，月球的傍晚才会降临。月球上的一天中，我们六次穿上太空服，走出牵引车，在月球表面搜寻有价值的矿物，或是为将来的月球探险者树起标识作为指引——都是些索然无趣的日常事务。

其实，所谓“月球探险”毫无危险可言，甚至无法让人兴奋起来。我们也可以在牵引车的压力舱中舒舒服服地呆上整整一个月，如果遇到麻烦，就用无线电求助，然后耐心坐等飞船来接。

是的，我说过，“月球探险”毫无刺激可言，可是，也并不全然如此。那些不可思议的群山没有人会看到厌倦，与它们相比，地球上所有的山峰都显得过于“温文尔雅”，而月球上的山峰则更加雄奇崔嵬。

海洋虽然已经消失，但留下许多尖岬与海角，谁也不知道经过哪一处，就会有怎样从未见过的壮丽景观展现在眼前。危海的整个南部地带曾经是一片开阔的三角洲，曾经的河流在这里注入大海，河道至今历历在目。那时，月球还年轻，处于短暂的火山活跃期，暴雨时时倾盆而下，冲刷着群山，汇入河道形成河流。每一处古老的山谷都仿佛是一个诱惑，邀请我们跨越未知的高地。可我们还有一百多英里的路要赶，只能远远地眺望一番，攀登它们的任务，就留给后人吧。

在牵引车里，我们恪守地球时间，每天22时整，把最后一次无线电信号发回主基地，我们就算结束了一天的工作。在外面，太阳仍然高悬，岩石被晒得滚烫，但对我们来说，已经进入“夜晚”。直到8小时后，我们再次醒来，压力舱里响起此起彼伏的电动剃须刀的嗡嗡声，一个人做早餐，还有人打开短波收音机，收听来自地球的消息。事实上，当煎香肠的味道充满压力舱的时候，你很难想象我们正处于一个完全陌生的世界——一切都那么自然，和在家里没什么两样。除了我们的体重略有减轻，东西掉落时有点慢吞吞而已。

那天轮到我做早餐，压力舱的一角是厨房。——这么多年过去了，那一刻记忆犹新——收音机里正在播放我最喜欢的曲子，一首威尔士民歌《白色岩石上的戴维》。我们的司机早已穿上太空服，在外面检查牵引车的履带。我的助手路易斯·加内特坐在前面的驾驶舱里，正在给昨天的考察日记做补充。

我站在煎锅前，觉得自己就像地球上的家庭主妇，正在等着香肠煎好，表皮炸开，一边漫不经心地看着窗外的群山，它们仿佛一堵墙，将南方的地平线遮得严严实实，向东西两个方向延展开去，直到随着月球的弧度消失。看上去它们仿佛就在一两英里远的地方，但我知道，最近的山峰也在二十英里之外。当然了，在月球上，你不会因为距离遥远而看不清楚——这里不像地球，没有空气，更没有雾气，即使是远处的物体，也不会模糊，更不会变形。

那些山峰都有一万英尺，山势险峻，从平原上拔地而起，仿佛许久之前，潜藏在地下的长牙忽然钻破熔融的地表，直刺苍穹。哪怕是最近的几座，山脚线也被参差起伏的平原地貌挡住，我们无缘得见。要知道，月球是个很小的世界，从我所在之处到前方的地平线，可能也只有两英里。

我望着群山之巅，那里还从未有过人类的足迹。早在人类到来之前，这些山峰就见证了海洋的枯竭，目睹了海水如何不甘地退回月心的墓穴，带走了这个星球的希望，也带走了这个世界生命的曙光。刺眼的阳光照在这些森严壁垒之上，反光足以灼伤人的眼睛。但就在顶峰之上，就是比地球的午夜还要漆黑的天幕，群星闪耀，它们的光芒从不曾黯淡。

我转过身，这时，我看见了一道金属的闪光。

——就在群山之中，一座向西伸展出三十英里的大海岬的山脊之上，一个看不清尺寸的发光点，就像一颗夜空中的星星，被险峻的群山捕获。

我猜想，一定是阳光照在某些平滑的岩石表面，反射回来映入我的眼睛。这种事并不罕见，在月球公转周期的第二阶段——即满月前一周——地球上的观察者有时还能观测到风暴洋中闪烁的大片的蓝白色光辉，那是阳光正照到风暴洋中的山峦之上，由一个世界反射到另一个世界的熠熠光芒。

但让我好奇的是，什么样的岩石能反射出如此耀眼的光呢？于是我爬进观测塔，转动四英寸直径的望远镜，向西方看去。

眼中所见让我的好奇心更甚，视野中的峰峦清晰无比，棱角分明，仿佛触手可及。但不管反光的是什么，它实在太小了，根本看不清。不过，那东西显然是对称的，造型优美，而承载它的山顶又平坦得出奇，我盯着那谜一般的物体，就像望着虚空……不知过了多久，忽然传来一股煳味！好嘛！这香肠跟着我们在月球表面颠簸了二十五万英里，结果都给浪费了。

整个上午，我们都在争论接下来该如何穿越危海。要是往西走，挡在前面的群山简直比天还要高。直到我们穿着太空服外出勘探时，仍然通过无线电在讨论这个问题。大家都同我说，月球上从来没有出现过任何智慧生物，曾经存在过的生命形式也不过是一些原始的植物，以及它们那些更低等的祖先，这是已经十分肯定的。我当然知道，但有的时候，作为一个科学家，绝不能害怕当傻瓜。

“听我说，”最后我说，“我必须去，就算是为了让我安心好了。那座山不到一万两千英尺——也就相当于地球重力下的两千英尺——一来一回，二十个小时足够了。再说了，我一直想爬到山上去看看，这也是个好机会。”

“就算你没摔断脖子，”加内特说，“等我们回到基地，你也会成为整个考察队的笑柄。从今以后，那座山也许会被命名为‘威尔逊傻冒山’。”

“我不会摔断脖子的，”我态度坚决，“你还记得第一个爬上皮科山和赫利孔山的人是谁吗？”

“那时候你可比现在年轻多了吧。”加内特温和地反问道。

“你这么一说，我更有理由上去看看了。”——为了尊严。

那天“晚上”，我们把牵引车停到距离那座海岬半英里的地方，早早休息。第二天一早，加内特陪我一起出发。他是个出色的登山运动员，以前经常和我一起探险。我们的司机留下来看设备，他显然求之不得。

乍一看，那些绝壁似乎完全无法攀爬，但对我们这些登山健将来说，这里的重力只有地球的六分之一，爬上去简直是小菜一碟。在月球登山，真正的危险是过度自信。要知道，即使是月球，从六百英尺高处跌下，也是会要人命的——就像地球上的一百英尺一样。

到了四千英尺的高度，我们在一块宽阔的岩架上停下来，第一次休息。爬山并不难，可是我很少做这种运动了，四肢有点僵硬，能休息一下当然很高兴。在这里，我们还能看见牵引车，就像一只小小的金属甲虫，远远地趴在悬崖脚下。我们告知了司机当前的高度，然后继续向上攀登。

太空服里很舒服，很凉爽，制冷装置帮我们抵挡灼热的阳光，还带走了大量运动产生的热量。我们没怎么交谈，除了递一下工具，或者商量一下接下来怎么爬。不知道加内特在想什么，或许在想，这是他干过的最疯狂的蠢事儿。——对此我表示同意，但登山自有乐趣，只要想想之前从未有人类达到此处，再看看越来越开阔的景致，你还想要什么别的回报呢？

来到岩壁前面，我并没有特别兴奋，远在三十英里处，我就用望远镜仔细地观察过它，它高出我们头顶五十英尺左右，那片平顶就在上方，诱使我来到这儿的东西就在上面。我几乎可以肯定，那东西不是很久很久以前，一块坠落的陨石留下的碎片，在这亘古不变、永不腐蚀的寂静世界里，它的断面依然平滑，依然闪闪发光。

岩壁上没有可以抓取的地方，我们只好用挂钩，我疲惫的双臂似乎又恢复了一点力气，把三指金属挂钩在头顶抡圆，然后朝着群星抛出。第一下抓空了，挂钩缓缓落下，我拉回绳索。到第三次的时候，钩爪牢牢地抓住了岩壁，就算我们俩的体重加在一起也不会脱落。

加内特有点担心地看着我，我敢说，他想自己先上去看看情况。但我隔着面罩玻璃冲他笑了笑，摇摇头，然后开始了最后一段攀爬。

这段攀爬用了点时间，即使加上太空服，在这里我也只有四十磅重，所以只靠双手就能拉动自己向上，不用借助脚的力量。到了边缘，我停了一下，朝下面的加内特招招手，然后翻身上去，站直身体，看着前方。

你必须要理解，直到这一刻之前，我依然几乎完全相信我要找的东西没有什么特别或奇异之处，但，“几乎完全”不等于“完全”，微弱的疑惑始终困扰着我，所以我才一路到了这里。

好吧，到了这里，“疑惑”烟消云散，但“困扰”才真正开始。

我站在高山之上，它在我面前一百英尺处，十分光滑——如此光滑以至于不可能天然形成——日复一日坠落的陨石没有在它表面上留下任何凹坑和划痕，它的外表仍然像一面镜子，反射着耀眼的光芒。它的造型像个金字塔，大概有两个人那么高，矗立在岩石上，就像一颗巨大的多切面的宝石。

最初的几秒钟，我的大脑一片空白，随后，一阵不可思议、难以言表的喜悦油然而生，在我胸中激荡翻滚。我爱月球，而现在我知道了，在阿里斯塔克斯和埃拉托斯特尼陨石坑中发现的苔藓植物，并非月球曾经孕育过的唯一的生命。第一批月球探险家怀抱的古老梦想虽然一直被质疑和否定，但事实上他们是对的，月球文明是存在的——而我是第一个发现它的人。

也许我来迟了，没能看到一亿年前这个文明的盛况，可是我并不沮丧，迟到好过永不，我终于来了，这已足够。

终于，我的脑子可以正常运转的时候，我开始思索：这是一幢房子？一座圣殿？还是别的我想不到用途的建筑？如果是房子，为什么要建在如此难以抵达的地方？我很好奇，难道这真的是一座神庙？我仿佛看到一群衣着怪异的祭司，向着他们的神明祈祷，而月球上的海洋正在枯竭，生命也将随之消亡，他们向着神明的祷告，最终只是徒然……

我向前走了十几步，更近地观察它，但出于谨慎，不敢靠得太近。我略懂一些考古学知识，于是试着猜测这个文明的发展水平，他们能够铲平一座山头，能够造出镜子一样的反光表面，这足以令我们心驰神往。

我甚至开始揣测，如果古代埃及的工匠们，得到这些更为古老的建筑师们使用的奇特材料，他们是否能造出这么一个建筑，应该可以，我觉得，因为这建筑并不大。说实话，当时我完全没有考虑到，眼前的事物是比人类更先进的物种制造的。——月球上曾经有过比人类更先进的物种？这个想法太惊人，太难以接受，我的自尊心让我一时无法做出这样的结论。

随后，我注意到了一件事，后脖颈一下子冰凉冰凉——这件事看似微不足道，所以一开始我完全没有注意到：这块平顶上留下了许多陨石撞击的痕迹，覆盖着几英寸厚的宇宙尘埃，只要没有风，这种尘埃会在世界上任何一个表面堆积下来。可是，所有的宇宙尘埃和陨石痕迹，在这座小金字塔周围突然止步，留下一个不小的干净的圆形区域，好像这里有一堵无形的墙，挡住了岁月的侵蚀，挡住了来自太空的、缓慢而永不止息的流星的空袭。

耳机里传来大喊大叫的声音，我这才意识到，加内特已经呼叫我好一阵子了。我梦游一样走到悬崖边缘，打手势叫他爬上来，现在我已经说不出话了。然后我又走向那闪闪发光的神秘建筑，捡起一块碎石子，朝它轻轻扔过去。哪怕小石子在无形的屏障前突然消失，我也不会惊讶，但它只是轻轻地滑落，好像碰到了一个光滑的半球型的表面。

这下我明白了，眼前这东西与人类的古迹完全不同，它不是建筑，而是一台机器，一种力量保护着它，向永恒发出挑战。这种力量，无论它是什么，至今仍在发挥着威力，而我也许已经靠得太近了。我想起了过去一个世纪里人们发现并掌握的各种射线，也许我已经走近了毫无遮蔽的原子反应堆前，正身处无声无形却致命的辐射之中。如果真是这样，那已经无可挽回，我在劫难逃。

我还记得，当时我转过身，朝加内特走过去，他也向我走来，站在我身旁，很久说不出话来。他甚至没注意到我，我也没有打扰他，只是走到绝壁边缘，极力理清思路。横躺在上万英尺之下的的正是危海——没错，危难之海——对大多数人来说，它既陌生又诡异，而我却对它非常熟悉。我抬起头，看到新月一般的地球正依偎在群星的摇篮之间，我想要知道，当年那些神秘的工匠们完成这里的工作时，地球上的云雾之下正发生着什么？石炭纪的原始丛林是不是仍然雾气蒸腾？第一批两栖动物是不是正跨越荒凉的海岸线，开始了对陆地的征程？还是更早，生命还未出现，地球还处在漫长的寂静与孤独之中？

别问我为什么这么久都没猜到真相——现在看来，真相显而易见。但我当时刚刚发现这一切，心中唯有兴奋，理所当然地认为那层无形的天然水晶罩壁是由月球上某个古老的文明种族建造的。然后，突然之间，一个想法冒了出来，一下子压倒了所有其他的设想——

这是外星人制造的。

对于月球来说，制造这个东西的，也是外星人。

二十年来，除了一些退化的植物，我们在月球上没有发现任何生命。月球文明并不存在。如果它曾经存在过，不管最终如何消亡，总会留下一星半点存在过的痕迹。

我又看了看闪闪发光的“小金字塔”，隔着一段距离，我看清楚了，它与周围的环境如此格格不入。由于兴奋，也由于疲惫，我忽然笑了起来，笑得浑身发抖，笑得歇斯底里，笑得像个傻瓜——我仿佛听见“小金字塔”在对我说：“很抱歉，在这里，我也是外来者。”

在那之后，用了二十年的时间，我们才打开那层无形的防护盾，接触到水晶罩下面的神秘装置。因为完全无法破解，我们只好动用原子弹的蛮力，把外罩彻底粉碎，到现在，在山上还能找到那些可爱的发光的碎片。

这些碎片已经没有用了，金字塔里的机械装置——如果它确实能算是机械装置的话——属于一种远远超出人类知识水平的技术，或许都超出了物理力学的范畴。

这让我们更加困惑。如今，人类的步伐已经踏上了太阳系所有的行星，一直以来人们都相信，地球是宇宙中唯一的智慧生物的家园，而在我们已知的世界中，任何失落的文明都不可能是那台装置的制造者，它周围厚厚的宇宙尘埃已经帮助我们测算出了它的“年龄”，早在地球的海洋中出现生命之前，它就已经在那里了。

当我们的世界的年纪只有现在的一半的时候，就有外星来客从群星之间出发，掠过我们的太阳系，途中留下了这个标识，然后继续上路。在人类破坏它们之前，它一直在履行着制造者赋予它的使命。至于这使命是什么，我们只能猜测。

在银河系中，有近千亿颗恒星绕着它们的轨道旋转。很久很久之前，在另一个太阳周围的世界中，已经有某个种族进化到超越我们现在已经到达的智慧高度。想一想他们的文明，可以一直追溯到宇宙诞生的光芒还未完全消散之时，他们是宇宙真正的主人，而那时的宇宙还如此年轻，生命的迹象才刚刚开始在一两颗星球上萌芽，他们会多么孤独。我们无法想象，这些孤独的神明穿越无限的时空，却找不到任何相似的种族来化解他们的寂寞。

他们一定找遍了无数的星团，正如我们找遍了太阳系每一颗行星。星球无处不在，但要么一片死寂，要么遍布着原始的爬虫。就连我们的地球，巨大的火山口仍在喷出滚滚浓烟，天空中雾霾密布。这时，黎明的众神乘坐最早的飞船，越过冥王星外围的宇宙深渊而来。他们飞过一颗又一颗冰封的行星，知道那里不可能出现生命，或许还曾在某颗行星上停留，向太阳的火焰暂时取一下暖，然后再次踏上征程。

这些星际漫游者一定注意到了地球，看着它在冰与火的夹缝之间安全地绕行，他们一定能够预见到，这是太阳最宠爱的孩子，就在这里，在遥远的未来，必将诞生智慧生命。

可是前方还有无数的星星在等着他们，而他们很可能永远也不会再回到这里。

于是，他们留下了一个岗哨。

或许在宇宙中，他们已经撒下了上百万个这样的岗哨，守护着所有可能诞生生命的世界。它就是一座灯塔，亘古以来一直发射着信号，只是地球对此一无所知。

那么，为什么水晶罩里的金字塔要放置在月球之上，而非地球？现在，你或许已经明白了。它的制造者们并不关心仍在野蛮状态下苦苦挣扎的种族，只有当我们的文明已经证明了自己——走出摇篮、离开地球、穿越太空——他们才会对我们产生兴趣。

这是所有的智慧种族或早或晚都将遇到的挑战。这挑战有两重含义——

首先，能否征服原子能？

其次，使用原子能的结果是生存，还是毁灭？

一旦我们越过了这个界限，一旦我们找到金字塔，并打破保护罩，余下的就只是时间问题了。

现在，岗哨的使命完成了，它的信号中断了，制造者们会注意到的，他们将会重新注视地球。

也许他们乐意帮助我们这个幼稚的文明，他们一定已经非常非常古老，而老人总是固执的，也许他们愿意照顾年轻的一代。也许。

如今，每当我仰望星空，总是会想，他们会穿越哪片星云而来？或者你可以这样理解，我们已经点起了烽火，发出了信号，然后，只有等待。

但我相信，不会等得太久。

————————————

读后——

在阿瑟·克拉克的短篇里，这篇是我最喜欢的。

我有理由相信，这一篇是他的“拉玛”系列的滥觞。但是，正如西尔弗伯格的长篇《日暮》，远不如阿西莫夫的同名短篇一样。即使是阿瑟·克拉克本人亲自操刀，“拉玛”四部曲也无法和这个6000字的短篇媲美。

我常常会忍不住比较阿瑟·克拉克和阿西莫夫笔下的宇宙，因为正是他们奠定了我的科幻观感和审美（——好吧，“三巨头”里海因莱因对我的影响要淡许多），如果说阿西莫夫的宇宙更加平衡、稳健、合情合理，有条不紊；那么阿瑟·克拉克的宇宙就要更险恶，更无情，更孤独，但也更诗意。

在阿西莫夫的宇宙中，人类磕磕绊绊、状况百出地向着群星而去，尽管一再陷入危机，而且总也摆脱不了愚昧，但始终有一条理性的防线，使我们能够用自己的力量守住最后的底线，迎来最终的光明；而在阿瑟·克拉克的宇宙中，超出人类想象和理解的巨大的谜题、可怕的危机、非凡的奇迹以及不可思议的美妙事物层出不穷，让人目眩神迷、心驰神往，但结局并非总是美好，结局也会浸满泪水，或是一片死寂……就像这个短篇，尽管在最后，“我”用热烈的语言憧憬着岗哨的制造者，“黎明的众神”、“宇宙最早的主人”、“孤独的先驱”……并相信他们会爱护和帮助我们这新生的幼稚的文明。但所有的读者读到这里，都能够感受到乐观的语言背后深藏的隐忧，是这样吗？也许吧。

这就是阿瑟·克拉克，因为这种不确定，因为这种挥之不去的隐忧和悲观，所以他的宇宙中更多了一重脆弱的美与诗意——如果我可以这么说的话，如果我一定要这么说的话——这样的宇宙，尽管更可怕，但我更喜欢。

The Sentinel
by Arthur C. Clarke
1951 Avon Periodicals Inc.

The next time you see the full moon high in the south, look carefully at its right-hand edge and let your eye travel upward along the curve of the disk. Round about two o’clock you will notice a small, dark oval: anyone with normal eyesight can find it quite easily. It is the great walled plain, one of the finest on the Moon, known as the Mare Crisium-the Sea of Crises. Three hundred miles in diameter, and almost completely surrounded by a ring of magnificent mountains, it had never been explored until we entered it in the late summer of 1996.

Our expedition was a large one. We had two heavy freighters which had flown our supplies and equipment from the main lunar base in the Mare Serenitatis, five hundred miles away. There were also three small rockets which were intended for short-range transport over regions which our surface vehicles couldn’t cross. Luckily, most of the Mare Crisiurn is very flat. There are none of the great crevasses so common and so dangerous elsewhere, and very few craters or mountains of any size. As far as we could tell, our powerful caterpillar tractors would have no difficulty in taking us wherever we wished to go.

I was geologist-or selenologist, if you want to be pedantic in charge of. the group exploring the southern region of the Mare. We had crossed a hundred miles of it in a week, skirting the foothills of the mountains along the shore of what was once the ancient sea, some thousand million years before. When life was beginning on Earth, it was already dying here. The waters were retreating down the flanks of those stupendous cliff s, retreating into the empty heart of the Moon. Over the land which we were crossing, the tideless ocean had once been half a mile deep, and now the only trace of moisture was the hoarfrost one could sometimes find in caves which the searing sunlight never penetrated.

We had begun our journey early in the slow lunar dawn, and still had almost a week of Earth-time before nightfall. Half a dozen times a day we would leave our vehicle and go outside in the spacesuits to hunt for interesting minerals, or to place markers for the guidance of future travelers.

It was an uneventful routine. There is nothing hazardous or even particularly exciting about lunar exploration. We could live comfortably for a month in our pressurized tractors, and if we ran into trouble we could always radio for help and sit tight until one of the spaceships came to our rescue.

I said just now that there was nothing exciting about lunar exploration, but of course that isn’t true. One could never grow tired of those incredible mountains, so much more rugged than the gentle hills of Earth. We never knew, as we rounded the capes and promontories of that vanished sea, what new splendors would be revealed to us. The whole southern curve of the Mare Crisiurn is a vast delta where a score of rivers once found their way into the ocean, fed perhaps by the torrential rains that must have lashed the mountains in the brief volcanic age when the Moon was young.

Each of these ancient valleys was an invitation, challenging us to climb into the unknown uplands beyond. But we had a hundred miles still to cover, and could only look longingly at the heights which others must scale.

We kept Earth-time aboard the tractor, and precisely at 22.00 hours the final radio message would be sent out to Base and we would close down for the day. Outside, the rocks would still be burning beneath the almost vertical sun, but to us it was night until we awoke again eight hours later. Then one of us would prepare breakfast, there would be a great buzzing of electric razors, and someone would switch on the short-wave radio from Earth. Indeed, when the smell of frying sausages began to fill the cabin, it was sometimes hard to believe that we were not back on our own world -everything was so normal and homely, apart from the feeling of decreased weight and the unnatural slowness with which objects fell.

It was my turn to prepare breakfast in the corner of the main cabin that served as a galley. I can remember that moment quite vividly after all these years, for the radio had just played one of my favorite melodies, the old Welsh air, “David of the White, Rock.”

Our driver was already outside in his space-suit, inspecting our caterpillar treads. My assistant, Louis Garnett, was up forward in the control position, making some belated entries in yesterday’s log.

As I stood by the frying pan waiting, like any terrestrial housewife, for the sausages to brown, I let my gaze wander idly over the mountain walls which covered the whole of the southern horizon, marching out of sight to east and west below the curve of the Moon. They seemed only a mile or two from the tractor, but I knew that the nearest was twenty miles away. On the Moon, of course, there is no loss of detail with distance-none of that almost imperceptible haziness which softens and sometimes transfigures all far-off things on Earth.

Those mountains were ten thousand feet high, and they climbed steeply out of the plain as if ages ago some subterranean eruption had smashed them skyward through the molten crust. The base of even the nearest was hidden from sight by the steeply curving surface of the plain, for the Moon is a very little world, and from where I was standing the horizon was only two miles away.

I lifted my eyes toward the peaks which no man had ever climbed, the peaks which, before the coming of terrestrial life, had watched the retreating oceans sink sullenly into their graves, taking with them the hope and the morning promise of a world. The sunlight was beating against those ramparts with a glare that hurt the eyes, yet only a little way above them the stars were shining steadily in a sky blacker than a winter midnight on Earth.

I was turning away when my eye caught a metallic glitter high on the ridge of a great promontory thrusting out into the sea thirty miles to the west. It was a dimensionless point of light, as if a star had been clawed from the sky by one of those cruel peaks, and I imagined that some smooth rock surface was catching the sunlight and heliographing it straight into my eyes. Such things were not uncommon. When the Moon is in her second quarter, observers on Earth can sometimes see the great ranges in the Oceanus Procellarum burning with a blue-white iridescence as the sunlight flashes from their slopes and leaps again from world to world. But I was curious to know what kind of rock could be shining so brightly up there, and I climbed into the observation turret and swung our four inch telescope round to the west.

I could see just enough to tantalize me. Clear and sharp in the field of vision, the mountain peaks seemed only half a mile away, but whatever was catching the sunlight was still too small to be resolved. Yet it seemed to have an elusive symmetry, and the summit upon which it rested was curiously flat. I stared for a long time at that glittering enigma, straining my eyes into space, until
presently a smell of burning from the galley told me that our breakfast sausages had made their quarter-million mile journey in vain.

All that morning we argued our way across the Mare Crisium while the western mountains reared higher in the sky. Even when we were out prospecting in the space-suits, the discussion would continue over the radio. It was absolutely certain, my companions argued, that there had never been any form of intelligent life on the Moon. The only living things that had ever existed there were a few primitive plants and their slightly less degenerate ancestors. I knew that as well as anyone, but there are times when a scientist must not be afraid to make a fool of himself.

“Listen,” I said at last, “I’m going up there, if only for my own peace of mind. That mountain’s less than twelve thousand feet high -that’s only two thousand under Earth gravity-and I can make the trip in twenty hours at the outside. I’ve always wanted to go up into those hills, anyway, and this gives me an excellent excuse.”

“If you don’t break your neck,” said Garnett, “you’ll be the laughing-stock of the expedition when we get back to Base. That mountain will probably be called Wilson’s Folly from now on.”

“I won’t break my neck,” I said firmly. “Who was the first man to climb Pico and Helicon?”

“But weren’t you rather younger in those days?” asked Louis gently.

“That,” I said with great dignity, “is as good a reason as any for going.”

We went to bed early that night, after driving the tractor to within half a mile of the promontory. Garnett was coming with me in the morning; he was a good climber, and had often been with me on such exploits before. Our driver was only too glad to be left in charge of the machine.

At first sight, those cliffs seemed completely unscalable, but to anyone with a good head for heights, climbing is easy on a world where all weights are only a sixth of their normal value. The real danger in lunar mountaineering lies in overconfidence; a six-hundred-foot drop on the Moon can kill you just as thoroughly as a. hundred-foot fall on Earth.

We made our first halt on a wide ledge about four thousand feet above the plain. Climbing had not been very difficult, but my limbs were stiff with the unaccustomed effort, and I was glad of the rest. We could still see the tractor as a tiny metal insect far down at the foot of the cliff, and we reported our progress to the driver before starting on the next ascent.

Inside our suits it was comfortably cool, for the refrigeration units were fighting the fierce sun and carrying away the body-heat of our exertions. We seldom spoke to each other, except to pass climbing instructions and to discuss our best plan of ascent. I do not know what Garnett was thinking, probably that this was the craziest goose-chase he had ever embarked upon. I more than half agreed with him, but the joy of climbing, the knowledge that no man had ever gone this way before and the exhilaration of the steadily widening landscape gave me all the reward I needed.

I don’t think I was particularly excited when I saw in front of us the wall of rock I had first inspected through the telescope from thirty miles away. It would level off about fifty feet above our heads, and there on the plateau would be the thing that had lured me over these barren wastes. It was, almost certainly, nothing more than a boulder splintered ages ago by a falling meteor, and with its cleavage planes still fresh and bright in this incorruptible, unchanging silence.

There were no hand-holds on the rock face, and we had to use a grapnel. My tired arms seemed to gain new strength as I swung the three-pronged metal anchor round my head and sent it sailing Lip
toward the stars. The first time it broke loose and came falling slowly back when we pulled the rope. On the third attempt, the prongs gripped firmly and our combined weights could not shift it.
Garnett looked at me anxiously. I could tell that he wanted to go first, but I smiled back at him through the glass of my helmet and shook my head. Slowly, taking my time, I began the final ascent.

Even with my space-suit, I weighed only forty pounds here, so I pulled myself up hand over hand without bothering to use my feet. At the rim I paused and waved to my companion, then I scrambled over the edge and stood upright, staring ahead of me.

You must understand that until this very moment I had been almost completely convinced that there could be nothing strange or unusual for me to find here. Almost, but not quite; it was that haunting doubt that had driven me forward. Well, it was a doubt no longer, but the haunting had scarcely begun.

I was standing on a plateau perhaps a hundred feet across. It had once been smooth-too smooth to be natural-but falling meteors had pitted and scored its surface through immeasurable eons. It had been leveled to support a glittering, roughly pyramidal structure, twice as high as a man, that was set in the rock like a gigantic, many-faceted jewel.

Probably no emotion at all filled my mind in those first few seconds. Then I felt a great lifting of my heart, and a strange, inexpressible joy. For I loved the Moon, and now I knew that the creeping moss of Aristarchus and Eratosthenes was not the only life she had brought forth in her youth. The old, discredited dream of the first explorers was true. There had, after all, been a lunar civilization-and I was the first to find it. That I had come perhaps a hundred million years too late did not distress me; it was enough to have come at all.

My mind was beginning to function normally, to analyze and to ask questions. Was this a building, a shrine-or something for which my language had no name? If a building, then why was it erected in so uniquely inaccessible a spot? I wondered if it might be a temple, and I could picture the adepts of some strange priesthood calling on their gods to preserve them as the life of the Moon ebbed with the dying oceans, and calling on their gods in vain.

I took a dozen steps forward to examine the thing more closely, but some sense of caution kept me from going too near. I knew a little of archaeology, and tried to guess the cultural level of the civilization that must have smoothed this mountain and raised the glittering mirror surfaces that still dazzled my eyes.

The Egyptians could have done it, I thought, if their workmen had possessed whatever strange materials these far more ancient architects had used. Because of the thing’s smallness, it did not occur to me that I might be looking at the handiwork of a race more advanced than my own. The idea that the Moon had possessed intelligence at all was still almost too tremendous to grasp, and my pride would not let me take the final, humiliating plunge.

And then I noticed something that set the scalp crawling at the back of my neck-something so trivial and so innocent that many would never have noticed it at all. I have said that the plateau was scarred by meteors; it was also coated inches-deep with the cosmic dust that is always filtering down upon the surface of any world where there are no winds to disturb it. Yet the dust and the meteor scratches ended quite abruptly in a wide circle enclosing the little pyramid, as though an invisible wall was protecting it from the ravages of time and the slow but ceaseless bombardment from space.

There was someone shouting in my earphones, and I realized that Garnett had been calling me for some time. I walked unsteadily to the edge of the cliff and signaled him to join me, not trusting myself to speak. Then I went back toward that circle in the dust. I picked up a fragment of splintered rock and tossed it gently toward the shining enigma. If the pebble had vanished at that invisible barrier I should not have been surprised, but it seemed to hit a smooth, hemispherical surface and slide gently to the ground.

I knew then that I was looking at nothing that could be matched in the antiquity of my own race.

This was not a building, but a machine, protecting itself with forces that had challenged Eternity. Those forces, whatever they might be, were still operating, and perhaps I had already come too close. I thought of all the radiations man had trapped and tamed in the past century. For all I knew, I might be as irrevocably doomed as if I had stepped into the deadly, silent aura of an unshielded atomic pile.

I remember turning then toward Garnett, who bad joined me and was now standing motionless at my side. He seemed quite oblivious to me, so I did not disturb him but walked to the edge of the cliff in an effort to marshal my thoughts. There below me lay the Mare Crisium-Sea of Crises, indeed-strange and weird to most men, but reassuringly familiar to me. I lifted my eyes toward the crescent Earth, lying in her cradle of stars, and I wondered what her clouds had covered when these unknown builders had finished their work. Was it the steaming jungle of the Carboniferous, the bleak shoreline over which the first amphibians must crawl to conquer the land-or, earlier still, the long loneliness before the coming of life?

Do not ask me why I did not guess the truth sooner-the truth, that seems so obvious now. In the first excitement of my discovery, I had assumed without question that this crystalline apparition had been built by some race belonging to the Moon’s remote past, but suddenly, and with overwhelming force, the belief came to me that it was as alien to the Moon as I myself.

In twenty years we had found no trace of life but a few degenerate plants. No lunar civilization, whatever its doom, could have left but a single token of its existence.

I looked at the shining pyramid again, and the more remote it seemed from anything that had to do with the Moon. And suddenly I felt myself shaking with a foolish, hysterical laughter, brought on by excitement and overexertion: for I had imagined that the little pyramid was speaking to me and was saying: “Sorry, I’m a stranger here myself.”

It has taken us twenty years to crack that invisible shield and to reach the machine inside those crystal walls. What we could not understand, we broke at last with the savage might of atomic power and now I have seen the fragments of the lovely, glittering thing I found up there on the mountain.

They are meaningless. The mechanisms-if indeed they are mechanisms-of the pyramid belong to a technology that lies far beyond our horizon, perhaps to the technology of para-physical forces.

The mystery haunts us all the more now that the other planets have been reached and we know that only Earth has ever been the home of intelligent life in our Universe. Nor could any lost civilization of our own world have built that machine, for the thickness of the meteoric dust on the plateau has enabled us to measure its age. It was set there upon its mountain before life had emerged from the seas of Earth.

When our world was half its present age, something from the stars swept through the Solar System, left this token of its passage, and went again upon its way. Until we destroyed it, that machine was still fulfilling the purpose of its builders; and as to that purpose, here is my guess.

Nearly a hundred thousand million stars are turning in the circle of the Milky Way, and long ago other races on the worlds of other suns must have scaled and passed the heights that we have reached. Think of such civilizations, far back in time against the fading afterglow of Creation, masters of a universe so young that life as yet had come only to a handful of worlds. Theirs would have been a loneliness we cannot imagine, the loneliness of gods looking out across infinity and finding none to share their thoughts.

They must have searched the star-clusters as we have searched the planets. Everywhere there would be worlds, but they would be empty or peopled with crawling, mindless things. Such was our own Earth, the smoke of the great volcanoes still staining the skies, when that first ship of the peoples of the dawn came sliding in from the abyss beyond Pluto. It passed the frozen outer worlds, knowing that life could play no part in their destinies. It came to rest among the inner planets, warming themselves around the fire of the Sun and waiting for their stories to begin.

Those wanderers must have looked on Earth, circling safely in the narrow zone between fire and ice, and must have guessed that it was the favorite of the Sun’s children. Here, in the distant future, would be intelligence; but there were countless stars before -them still, and they might never come this way again.

So they left a sentinel, one of millions they have scattered throughout the Universe, watching over all worlds with the promise of life. It was a beacon that down the ages has been patiently signaling the fact that no one had discovered it.

Perhaps you understand now why that crystal pyramid was set upon the Moon instead of on the Earth. Its builders were not concerned with races still struggling up from savagery. They would be interested in our civilization only if we proved our fitness to survive -by crossing space and so escaping from the Earth, our cradle. That is the challenge that all intelligent races must meet, sooner or later. It is a double challenge, for it depends in turn upon the conquest of atomic energy and the last choice between life and death.

Once we had passed that crisis, it was only a matter of time before we found the pyramid and forced it open. Now its signals have ceased, and those whose duty it is will be turning their minds upon Earth. Perhaps they wish to help our infant civilization. But they must be very, very old, and the old are often insanely jealous of the young.

I can never look now at the Milky Way without wondering from which of those banked clouds of stars the emissaries are coming. If you will pardon so commonplace a simile, we have set off the fire-alarm and have nothing to do but to wait.

I do not think we will have to wait for long.