A real thinker, however, if confronted with the same problem, will look for a solution from every possible viewpoint. But failing an answer he will not give up. Instead he will let the subject drop for a while, say a couple of weeks or perhaps longer, and then refer to it again. This time he will find that certain obscurities have become a little clearer; that certain questions have been answered. He will again attack his puzzle with energy. And if he does not obtain a complete solution he will once more put it aside, returning to it after another interval, until finally a satisfactory solution presents itself. You may fail to see any difference between thinking for two hours separated by two weeks, and thinking for two consecutive hours. As an experiment, then, the next time you come across a puzzle which you fail to solve at first tilt, write down all the unsatisfactory solutions suggested, and all the questions, difficulties and objections met with. You may leave this for a few weeks. When you return to it a few of the difficulties will look less formidable, and some of the questions will have practically answered themselves. (Of course some of the difficulties may look more formidable, and a few new questions may have arisen.) If a solution is not found at the second attempt, the problem may again be sent to your mental waiting room. But if it is only of reasonable difficulty a solution is bound, soon or late, to be discovered. It is difficult to say just what effects this change in thought, when apparently one has engaged in no reflection during the interval. The attempted solution probably gives a certain “set” to our minds. Without being aware of it we observe facts relating to our problem. Ideas which occur to us in other connections are unconsciously seen in their bearing on the unsolved question. In short, “those proclivities of thought which have probably been caused unawares by experience” make themselves felt.