Introduction
My reader, before you proceed to the reading of this work, let us come to a preliminary agreements
That which you are going to read in this book has, it is true, been thought by me; but it matters not, either to you or to me, that you should know what I have thought. However much it may have been your habit to read works merely in order to know what their authors have thought and said, I still wish that you should proceed differently in respect to this book. I appeal not to your memory, but to your understanding. My object is not that you should remark what I have said, but that you should yourself think, and, if it pleases heaven, think precisely what I have thought. Hence, if in the reading of this work it should happen to you—as so often happens to readers now-a-days—that you should continue to read, without continuing to think—that you should still be taking hold of the words, without, however, continuing to seize their meaning—desist, redouble your attention, and read over again from the sentence where your attention slipped off, or put the book aside for the day, and commence tomorrow with fresh vigor. Only on this condition on your part can I fulfil the proud promise on the title-page—to force you to an understanding. You must really come out with your mind and oppose it to mine for battle, and to this I cannot force you. If you hold back, I have lost the wager; you will understand nothing, just as you can see nothing if you close your eyes.
But if it should happen to you that from a certain point in this work you cannot in any manner, and by any exertion, convince yourself of the correctness of my assertions, put the book aside, and leave it unread for a considerable time. Continue to use your understanding in the accustomed manner, without thinking about the book; and, perhaps, all of a sudden, without your intending it in any way, the condition of understanding it will come of itself, and you will after a while comprehend quite readily and well what at present you cannot comprehend by any exertion. Such things have also occurred to us, who at present claim some power of thinking. But let me entreat you to give God the praise for it, and to keep utterly silent on this subject until the condition of understanding this work, and its comprehension, have arisen in you.
My argument is one uninterrupted chain of conclusions; each subsequent point is true only on condition of its preceding point having been found to be true by you. If it has not been so found by you, you cannot continue to think as I have thought, and hence your persisting to read would have no other result than to make you acquainted with what I have thought. But this result has always been considered by me as very insignificant; and I have often marvelled at the modesty of most men in placing such a high value upon the thoughts of others, and so little value upon their own, that they will rather spend their whole lives in making themselves acquainted with those, than generate any of their own—a modesty which I desire should be utterly waived in the case of my thoughts.
By observing the external world, and his own internal self, each man of healthy senses receives a collection of cognitions, experiences, and facts. These, the given of immediate perception, he can also renew in himself without that actual perception; he can reflect upon and can hold the manifold of the perception together; can hunt up that wherein the separates of the manifold agree, and that wherein they do not agree. In this manner, if a man has but an ordinary, healthy understanding, his knowledge will become clearer, more definite, and useful—will become a possession, which he can administer with complete freedom and agility—but on no account will his knowledge be increased by thus reflecting upon it. He can reflect only upon what he has perceivedor observed, and can compareit only with itself, but on no account can he producenew objects by mere thinking.
This collection of knowledge, and a certain more or less superficial or thorough control over it by freely reflecting upon it, you and I and all men possess in common; and this is doubtless what is meant when people speak of a system or of propositions of common sense.