If we are ever to understand man, his conduct and reasoning, and if we aspire to learn to guide his life and his relations with his fellows more happily than heretofore, we cannot neglect the great discoveries briefly noted above. We must reconcile ourselves to novel and revolutionary conceptions of the mind, for it is clear that the older philosophers, whose works still determine our current views, had a very superficial notion of the subject with which they dealt. But for our purposes, with due regard to what has just been said and to much that has necessarily been left unsaid (and with the indulgence of those who will at first be inclined to dissent), _we shall consider mind chiefly as conscious knowledge and intelligence, as what we know and our attitude toward it--our disposition to increase our information, classify it, criticize it and apply it_. We do not think enough about thinking, and much of our confusion is the result of current illusions in regard to it. Let us forget for the moment any impressions we may have derived from the philosophers, and see what seems to happen in ourselves. The first thing that we notice is that our thought moves with such incredible rapidity that it is almost impossible to arrest any specimen of it long enough to have a look at it. When we are offered a penny for our thoughts we always find that we have recently had so many things in mind that we can easily make a selection which will not compromise us too nakedly. On inspection we shall find that even if we are not downright ashamed of a great part of our spontaneous thinking it is far too intimate, personal, ignoble or trivial to permit us to reveal more than a small part of it. I believe this must be true of everyone. We do not, of course, know what goes on in other people's heads. They tell us very little and we tell them very little. The spigot of speech, rarely fully opened, could never emit more than driblets of the ever renewed hogshead of thought--_noch grösser wie's Heidelberger Fass_. We find it hard to believe that other people's thoughts are as silly as our own, but they probably are.