One of the most painful circumstances of recent advances in science is that each one of them makes us know less than we thought we did. When I was young we all knew, or thought we knew, that a man consists of a soul and a body; that the body is in time and space, but the soul is in time only. Whether the soul survives death was a matter as to which opinions might differ, but that there is a soul was thought to be indubitable. As for the body, the plain man of course considered its existence self-evident, and so did the man of science, but the philosopher was apt to analyze it away after one fashion or another, reducing it usually to ideas in the mind of the man who had the body and anybody else who happened to notice him. The philosopher, however, was not taken seriously, and science remained comfortably materialistic, even in the hands of quite orthodox scientists.

    Nowadays these fine old simplicities are lost: physicists assure us that there is no such thing as matter, and psychologists assure us that there is no such thing as mind. This is an unprecedented occurrence. Who ever heard of a cobbler saying that there was no such thing as boots, or a tailor maintaining that all men are really naked? Yet that would have been no odder than what physicists and certain psychologists have been doing. To begin with the latter, some of them attempt to

    reduce everything that seems to be mental activity to an activity of the body. There are, however, various difficulties in the way of reducing mental activity to physical activity. I do not think we can yet say with any assurance whether these difficulties are or are not insuperable. What we can say, on the basis of physics itself, is that what we have hitherto called our body is really an elaborate scientific construction not corresponding to any physical reality. The modem would-be materialist thus finds himself in a curious position, for, while he may with a certain degree of success reduce the activities of the mind to those of the body, he cannot explain away the fact that the body itself is merely a convenient concept invented by the mind. We find ourselves thus going round and round in a circle: mind is an emanation of body, and body is an invention of mind. Evidently this cannot be quite right, and we have to look for something that is neither mind nor body, out of which both can spring.

    Let us begin with the body. The plain man thinks that material objects must certainly exist, since they are evident to the senses. Whatever else may be doubted, it is certain that anything you can bump into must be real; this is the plain man's metaphysic. This is all very well, but the physicist comes along and shows that you never bump into anything: even when you run your head against a stone wall, you do not really touch it. When you think you touch a thing, there are certain electrons and protons, forming part of your body, which are attracted and repelled by certain electrons and protons in the thing you think you are touching, but there is no actual contact. The electrons and protons in your body, becoming agitated by nearness to the other electrons and protons, are disturbed, and transmit a disturbance along your nerves to the brain; the effect in the brain is what is necessary to your sensation of contact, and by suitable experiments this sensation can be made quite deceptive. The electrons and protons themselves, however, are only a crude first approximation, a way of collecting into a bundle either trains of waves or the statistical probabilities of serious different kinds of events. Thus matter has become altogether too ghostly to be used as an adequate stick with which to beat the mind. Matter in motion, which used to seem so unquestionable, turns out to be a concept quite inadequate for the needs of physics.

    Nevertheless modern science gives no indication whatever of the existence of the soul or mind as an entity; indeed the reasons for disbelieving in it are of very much the same kind as the reasons for disbelieving in matter. Mind and matter were something like the lion and the unicorn fighting for the crown; the end of the battle is not the victory of one or the other, but the discovery that both are only heraldic inventions. The world consists of events, not of things that endure for a long time and have changing properties. Events can be collected into groups by their causal relations. If the causal relations are of one sort the resulting group of events may be called a physical object, and if the causal relations are of another sort, the resulting group may be called a mind. Any event that occurs inside a man's head will belong to groups of both kinds; considered as belonging to a group of one kind, it is a constituent of his brain, and considered as belonging to a group of the other kind, it is a constituent of his mind.

    Thus both mind and matter are merely convenient ways of organizing events. There can be no reason for supposing that either a piece of mind or a piece of matter is immortal. The sun is supposed to be losing matter at the rate of millions of tons a minute. The most essential characteristic of mind is memory, and there is no reason whatever to suppose that the memory associated with a given person survive, that person's death. Indeed there is every reason to think the opposite, for memory is clearly connected with a certain kind of brain structure, and since this structure decays at death, there is every reason to suppose that memory also must cease. Although metaphysical materialism cannot be considered true, yet emotionally the world is pretty much the same as it would be if the materialists were in the right. I think the opponents of materialism have always been actuated by two main desires: the first to prove that the mind is immortal, and the second to prove that the ultimate power in the universe is mental rather than physical. In both these respects, I think the materialists were in the right. Our desires, it is true, have considerable power on the earth's surface; the greater part of the land on this planet has a quite different aspect from that which it would have if men had not utilized it to extract food and wealth. But our power is very strictly limited. We cannot at present do anything whatever to the sun or moon or even to the interior of the earth, and there is not the faintest reason to suppose that what happens in regions to which our power does not extend has any mental causes. That is to say, to put the matter in a nutshell, there is no reason to think that except on the earth's surface anything happens because somebody wishes it to happen. And since our power on the earth's surface is entirely dependent upon the supply of energy which the earth derives from the sun, we are necessarily dependent upon the sun, and could hardly realize any of our wishes if the sun grew cold. It is of course rash to dogmatize as to what science may achieve in the future. We may learn to prolong human existence longer than now seems possible, but if there is any truth in modem physics, more particularly in the second law of thermo-dynamics, we cannot hope that the human race will continue for ever. Some people may find this conclusion gloomy, but if we are honest with ourselves, we shall have to admit that what is going to happen many millions of years hence has no very great emotional interest for us here and now. And science, while it diminishes our cosmic pretensions, enormously increases our terrestrial comfort. That is why, in spite of the horror of the theologians, science has on the whole been tolerated.

    近来科学进步中的最不幸事情之一就是，每一件新成就都让我们对世界的理解比以往更少。当我年轻时，我们都知道，或者我们认为自己知道，一个人由一个灵魂和一个身体组成。而且，那个身体存在于时间和空间中，而那个灵魂则只存在于时间中。至于灵魂是不是可以超越死亡，确实是仁者见仁智者见智，不过灵魂存在的事实应该是无可争议的。对普通人而言，身体的存在是不证自明的，科学家也这么想。而哲学家，则倾向于以这种方式或者那种方式把身体分析得如此疏远，好像身体通常只存在于一个拥有身体的人的精神中或者任何一个恰巧看见那个人的另一个人的观念中。不过，哲学家的这些怪想法并不为世人所重视，而在科学领域，即使是最正统的科学家也是唯物主义的。

    现在，往时那些简单明了的美景已然消逝。物理学家告诉我们，物质这种东西事实上并不存在，心理学家则声称，世界上根本没有所谓精神。这是前所未有的景象。有谁听到一个补鞋匠自己说，事实上没有靴子这种东西？或者一个裁缝师说，世界上所有人都没穿过衣服？如果他们这么说，也并不比现在的科学家和心理学家说得更怪诞。咱们先看看心理学家，某些心理学家正试图把所有看来是精神的活动划归到身体活动的层次上去。当然，把精神活动归纳到生理活动层次去，也有很多困难。我不相信人们已经有把握确信这些困难是可以克服的，还是根本不可逾越的。我们只能说，到目前为止，所谓的我们的身体是一个真正的科学构造并不与任何物质现实相对应。在此，一个现代的自称为唯物主义者的人，会发现自己陷入一种奇怪的两难境地。一方面，他在一定程度上成功地把自己的心理活动归纳到生理活动中去，另方面，他又没法摆脱这样的事实，即所谓身体其本身只不过是他的意识发明出来的方便解释道理的一个观念而已。这时，我们在一个陷阱里绕圈圈：精神是身体功能的一种外射，而身体不过是精神活动的一个发明。很明显，这不可能是正确的。我们必须找到另外的来源，既不是精神，也不是身体，而无论精神还是身体都能够发源于这个根本。

    让我们从身体开始。普通人想，物质的东西肯定存在，因为它们很容易为感官所感知。不管其他什么可以被怀疑，一个你猛地碰撞上了的东西，肯定是真实的。这是一个普通人的形而上学。这当然不错。不过，一个物理学家会过来，他会向你展示，你永远也不会碰撞上任何东西，即使你用你的脑袋猛地撞上了一道石墙，你也不会真正地碰上它！当你想你触到一样东西，肯定有一些电子和质子组成了你身体的一部分，这些电子和质子必然被你认为你碰触到的东西里的一些电子和质子所吸引和排斥，但他们之间并不发生真正的接触。你身体里的电子和质子由于接近了那个东西里的电子和质子而被激发，这些激烈运动的电子和质子就发射一种扰动，沿着你的神经系统传导到你的大脑，这些传输的效果就是你脑海里的所谓碰撞的感官感受。即使没有这种接触，通过适宜的实验，也可以把这种感受效果做得十分逼真。那些电子和质子，不过是一种原初的基本的近似性存在，是将一系列的波或者一系列不同事件的统计上的可能性集束在一起的方式而已。这样，物质就显得太过飘渺虚幻，难以像一根现实的棍棒去敲击精神。运动的物质，以往看起来那么不容置疑，现在已经成为一个无法满足物理学需要的观念。

    不过，现代科学没有对灵魂或者精神的存在给出任何明示，确实，不相信灵魂或精神的理由，在很大程度上与不相信物质的理由一样。精神和物质有点像狮子和独角兽在为皇冠而争斗，其结局不是一方或另一方的胜利，而是发现他们双方都只是起标识作用的发明。世界不是由东西构成的，而是由存在了很久的不断变化的事件构成。事件可以由它们之间的偶发关系集束到组合里。如果那些偶发关系属于某种类型，就把这一组合里的事件称为物体，如果属于另一种类型，就称之为精神。一个人脑子里发生的任一事件可以归类到两种类型的任一类中。当归集为其中一类时，它就是构成他的大脑的一部分，当归集到其中的另一类时，它就是构成他的精神的一部分。

    这样，精神和物质只不过是用于对事件进行组合的权宜性方式而已。也就没有理由去假设是精神是不朽的，或者物质是不朽的。太阳正以每分钟几百万吨的速度失去自己的物质和存在。精神的核心特征是记忆，并且没有任何理由去设想一个特定的人在他死后，其记忆还存活。当然，也可以有充足的理由去做相反的设想。因为可以十分清楚地说，记忆与大脑的某种构造相关联，当这种生理构造在身体死亡后腐烂了，就有充足的理由相信这种记忆也随着生理构造的腐烂而必然停息。虽然形而上学的唯物主义不能被人信为真理，不过，从情感上说，即使唯物主义是对的，世界也不会与它应该是的样子相差多远。我想，唯物主义的对手往往被两种冲动所驱使，一是要证明精神的不朽；其次是要证明宇宙的终极动力是精神性的，而不是物质性的。对于这两个问题，我想唯物主义是对的。在地球表层的活动领域，我们的欲望的确显现了惊人的力量。但在这个星球的更大部分上，如果人们不是用于生产食品和财富的话，必显现十分不同的特征。我们的力量实际上十分有限。当下，我们根本不能对太阳，或者月亮，或者地球的内部领域有任何作为。并且也没有丝毫理由去设想在那些人类力量所不及的人迹罕至的地方发生的事情里有多少精神的因素参与其中。也就是，简单地说，没有任何理由去相信在地球表面之外任一地方发生的任何事情起源于某人希望它发生。而且，因为我们在地球表面上表现出的力量最终决定于地球从太阳获取的能量，我们实际上依赖于太阳的供给，因而，不可能设想太阳变冷后还可以实现人类的任何期望。我们当然不能武断地断言，未来属于哪种科学。我们可能可以学会如何让人类能够存在得比现在看起来更长久。但如果现代物理学有一定的真理，特别是如果第二热力学定律是对的，那么我们就不能想象人类可以永久存在。某些人可能发现这些结论有些悲观，但如果我们诚恳待己，我们就不能不承认，那些可能发生于几百万年后的事情，对我们此时此刻的感情不会有多大影响。至于科学，因为它已经缩减了我们在宇宙领域上的前景，也就极大地提升了我们在有限区域内的舒适感。这也是为什么尽管引起了神学家的恐惧，科学在总体上还是可以忍受的。