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.

    近來科學進步中的最不幸事情之一就是，每一件新成就都讓我們對世界的理解比以往更少。當我年輕時，我們都知道，或者我們認為自己知道，一個人由一個靈魂和一個身體組成。而且，那個身體存在于時間和空間中，而那個靈魂則只存在于時間中。至于靈魂是不是可以超越死亡，確實是仁者見仁智者見智，不過靈魂存在的事實應該是無可爭議的。對普通人而言，身體的存在是不證自明的，科學家也這么想。而哲學家，則傾向于以這種方式或者那種方式把身體分析得如此疏遠，好像身體通常只存在于一個擁有身體的人的精神中或者任何一個恰巧看見那個人的另一個人的觀念中。不過，哲學家的這些怪想法并不為世人所重視，而在科學領域，即使是最正統的科學家也是唯物主義的。

    現在，往時那些簡單明了的美景已然消逝。物理學家告訴我們，物質這種東西事實上并不存在，心理學家則聲稱，世界上根本沒有所謂精神。這是前所未有的景象。有誰聽到一個補鞋匠自己說，事實上沒有靴子這種東西？或者一個裁縫師說，世界上所有人都沒穿過衣服？如果他們這么說，也并不比現在的科學家和心理學家說得更怪誕。咱們先看看心理學家，某些心理學家正試圖把所有看來是精神的活動劃歸到身體活動的層次上去。當然，把精神活動歸納到生理活動層次去，也有很多困難。我不相信人們已經有把握確信這些困難是可以克服的，還是根本不可逾越的。我們只能說，到目前為止，所謂的我們的身體是一個真正的科學構造并不與任何物質現實相對應。在此，一個現代的自稱為唯物主義者的人，會發現自己陷入一種奇怪的兩難境地。一方面，他在一定程度上成功地把自己的心理活動歸納到生理活動中去，另方面，他又沒法擺脫這樣的事實，即所謂身體其本身只不過是他的意識發明出來的方便解釋道理的一個觀念而已。這時，我們在一個陷阱里繞圈圈：精神是身體功能的一種外射，而身體不過是精神活動的一個發明。很明顯，這不可能是正確的。我們必須找到另外的來源，既不是精神，也不是身體，而無論精神還是身體都能夠發源于這個根本。

    讓我們從身體開始。普通人想，物質的東西肯定存在，因為它們很容易為感官所感知。不管其他什么可以被懷疑，一個你猛地碰撞上了的東西，肯定是真實的。這是一個普通人的形而上學。這當然不錯。不過，一個物理學家會過來，他會向你展示，你永遠也不會碰撞上任何東西，即使你用你的腦袋猛地撞上了一道石墻，你也不會真正地碰上它！當你想你觸到一樣東西，肯定有一些電子和質子組成了你身體的一部分，這些電子和質子必然被你認為你碰觸到的東西里的一些電子和質子所吸引和排斥，但他們之間并不發生真正的接觸。你身體里的電子和質子由于接近了那個東西里的電子和質子而被激發，這些激烈運動的電子和質子就發射一種擾動，沿著你的神經系統傳導到你的大腦，這些傳輸的效果就是你腦海里的所謂碰撞的感官感受。即使沒有這種接觸，通過適宜的實驗，也可以把這種感受效果做得十分逼真。那些電子和質子，不過是一種原初的基本的近似性存在，是將一系列的波或者一系列不同事件的統計上的可能性集束在一起的方式而已。這樣，物質就顯得太過飄渺虛幻，難以像一根現實的棍棒去敲擊精神。運動的物質，以往看起來那么不容置疑，現在已經成為一個無法滿足物理學需要的觀念。

    不過，現代科學沒有對靈魂或者精神的存在給出任何明示，確實，不相信靈魂或精神的理由，在很大程度上與不相信物質的理由一樣。精神和物質有點像獅子和獨角獸在為皇冠而爭斗，其結局不是一方或另一方的勝利，而是發現他們雙方都只是起標識作用的發明。世界不是由東西構成的，而是由存在了很久的不斷變化的事件構成。事件可以由它們之間的偶發關系集束到組合里。如果那些偶發關系屬于某種類型，就把這一組合里的事件稱為物體，如果屬于另一種類型，就稱之為精神。一個人腦子里發生的任一事件可以歸類到兩種類型的任一類中。當歸集為其中一類時，它就是構成他的大腦的一部分，當歸集到其中的另一類時，它就是構成他的精神的一部分。

    這樣，精神和物質只不過是用于對事件進行組合的權宜性方式而已。也就沒有理由去假設是精神是不朽的，或者物質是不朽的。太陽正以每分鐘幾百萬噸的速度失去自己的物質和存在。精神的核心特征是記憶，并且沒有任何理由去設想一個特定的人在他死后，其記憶還存活。當然，也可以有充足的理由去做相反的設想。因為可以十分清楚地說，記憶與大腦的某種構造相關聯，當這種生理構造在身體死亡后腐爛了，就有充足的理由相信這種記憶也隨著生理構造的腐爛而必然停息。雖然形而上學的唯物主義不能被人信為真理，不過，從情感上說，即使唯物主義是對的，世界也不會與它應該是的樣子相差多遠。我想，唯物主義的對手往往被兩種沖動所驅使，一是要證明精神的不朽；其次是要證明宇宙的終極動力是精神性的，而不是物質性的。對于這兩個問題，我想唯物主義是對的。在地球表層的活動領域，我們的欲望的確顯現了驚人的力量。但在這個星球的更大部分上，如果人們不是用于生產食品和財富的話，必顯現十分不同的特征。我們的力量實際上十分有限。當下，我們根本不能對太陽，或者月亮，或者地球的內部領域有任何作為。并且也沒有絲毫理由去設想在那些人類力量所不及的人跡罕至的地方發生的事情里有多少精神的因素參與其中。也就是，簡單地說，沒有任何理由去相信在地球表面之外任一地方發生的任何事情起源于某人希望它發生。而且，因為我們在地球表面上表現出的力量最終決定于地球從太陽獲取的能量，我們實際上依賴于太陽的供給，因而，不可能設想太陽變冷后還可以實現人類的任何期望。我們當然不能武斷地斷言，未來屬于哪種科學。我們可能可以學會如何讓人類能夠存在得比現在看起來更長久。但如果現代物理學有一定的真理，特別是如果第二熱力學定律是對的，那么我們就不能想象人類可以永久存在。某些人可能發現這些結論有些悲觀，但如果我們誠懇待己，我們就不能不承認，那些可能發生于幾百萬年后的事情，對我們此時此刻的感情不會有多大影響。至于科學，因為它已經縮減了我們在宇宙領域上的前景，也就極大地提升了我們在有限區域內的舒適感。這也是為什么盡管引起了神學家的恐懼，科學在總體上還是可以忍受的。