我想這篇也可以叫做「睡覺的工作」吧，不只是你我有這樣的經驗：熬夜怎麼想都想不通的問題，睡完一覺就想通了。連數學大師波利亞也有過類似的經驗。所以，還是先睡覺吧！(蓋)
摘自 << 怎樣解題 >> 潛意識的工作 波利亞
有一天晚上，我與一位朋友在討論某位作者的作品，但是我卻忽然想不起這位作者名字。當時，我在覺得很懊惱，因為他的某部作品，我其實記得很清楚。我還記得他的一些私人故事，那也是我當時想說的事；事實上，我記得每一件事，就獨獨想不起來他的名字。我一再回想他的名字，卻徒勞無功。隔天早晨，就在我想到前晚那個令人懊惱的情形的同時，他的名字竟自然跳出來，而且不費吹灰之力。
你應該也有很多類似的經驗。甚至，如果你曾經很熱切地投入某個問題中，也許對那個問題也有類似的經驗：譬如你很努力、很投入、想要解決某個問題，卻一點收穫也沒有，然而再經過一晚充分的休息，或是中斷個幾天之後，忽然產生一個靈感，讓你輕易地就把那個問題給解決了。問題本質為何，並不重要；不論是回想人名、猜一個困難的字謎，或是解數學問題，都會產生這種情形。
這種經驗，讓我們體會到什麼是潛意識的工作。當我們對某個問題的思考，暫停了一段長時間之後，它又會以某種更為清晰的方式，回到我們的意識中，而且往往讓我們比當初中斷思考的時候，更為接近解答。是誰去釐清了這些思緒？是誰把我們帶向解答？很明顯地，答案正是我們自己，我們在潛意識裡完成了這項工作。除此之外，實在找不出其他的答案。不論潛意識學說的價值為何，可以確定的是，在某個極限之後，我們就不應該太壓榨或強迫我們的意識去思考。在某些時候，暫時離開一下苦思很久的題目，並不是件壞事。「去找你的枕頭商量」，就是一句古老的建言。讓問題、也讓我們自己有休息的時間，往往在隔天就能更輕鬆地找到更多想法。「今天不行的，也許明天就可以了」，則是另一句古諺。
值得注意的是，在暫時思考之前，對問題的思考還是要先「告個段落」；至少要把能處理的小地方，先處理好，或是先大致釐清問題裡的某個層面。
只有是我們熱切期盼解答的問題，或是我們絞盡腦汁之後才暫停的問題，才會在下次在回來時，獲得「神奇的」改善；似乎為有義事上的努力與辛勞，才能啟動潛意識，讓它為我們工作。若不是這樣，那麼天下就太平了；因為我們只需要靠睡覺和發呆，就能產生解決難題的靈感。
以前的人，認為突然得到靈感或好點子，是上帝的恩賜，所以有「神來之筆」的說法。但是事實上，你必須先有足夠的努力，或至少足夠的渴望，這份恩典才會降臨。
原文下載 <<How to Solve It>> http://serl.iiit.ac.in/cs6600/book.pdf
Subconscious work. One evening I wished to discuss with a friend a certain author but I could not remember the author’s name. I was annoyed, because I remembered fairly well one of his stories. I remembered also some story about the author himself which I wanted to tell; I remembered, in fact, everything except the name. Repeatedly, I tried to recollect that name but all in vain. The next morning, as soon as I thought of the annoyance of the evening before, the name occurred to me without any effort.
The reader, very likely, remembers some similar experience of his own. And, if he is a passionate problemsolver. he has probably had some similar experience with problems. It often happens that you have no success at all with a problem; you work very hard yet without finding anything. But when you come back to the problem after a night’s rest, or a few days’ interruption, a bright idea appears and you solve the problem easily. The nature of the problem matters little; a forgotten word, a difficult word from a crossword-puzzle. the beginning of an annoying letter, or the solution of a mathematical problem may occur in this way.
Such happenings give the impression of subconscious work. The fact is that a problem, after prolonged absence, may return into consciousness essentially clarified, much nearer to its solution than it was when it dropped out of consciousness. Who clarified it, who brought it nearer to the solution? Obviously, oneself, working at it subconsciously. It is difficult to give any other answer; although psychologists have discovered the beginnings of another answer which may turn out some day to be more satisfactory.
Whatever may or may not be the merits of the theory of subconscious work. It is certain that there is a limit beyond which we should not force the conscious reflection. There are certain moments in which it is better to leave the problem alone for a while. “Take counsel of your pillow” is an old piece of advice. Allowing an interval of rest to the problem and to ourselves, we may obtain more tomorrow with less effort. “If today will not, tomorrow may” is another old saying. But it is desirable not to set aside a problem to which we wish to come back later without the impression of some achievement; at least some little point should be settled, some aspect of the question somewhat elucidated when we quit working.
Only such problems come back improved whose solution we passionately desire. or for which we have worked with great tension; conscious effort and tension seem to be necessary to set the subconscious work going. At any rate, it would be too easy if it were not so; we could solve difficult problems just by sleeping and waiting for a bright idea.
Past ages regarded a sudden good idea as an inspiration, a gift of the gods. You must deserve such a gift by work, or at least by a fervent wish.