If I am to listen to another man's opinion, it must be expressed positively. Of things problematical I have enough in myself. Piety is not an end, but a means: a means of attaining the highest culture by the purest tranquility of soul. Hence it may be observed that those who set up piety as an end and object are mostly hypocrites. Reading ought to mean understanding; writing ought to mean knowing something; believing ought to mean comprehending; when you desire a thing, you will have to take it; when you demand it, you will not get it; and when you are experienced, you ought to be useful to others. The stream is friendly to the miller whom it serves; it likes to pour over the mill wheels; what is the good of it stealing through the valley in apathy? Theory is in itself of no use, except in so far as it makes us believe in the connection of phenomena. "_Le sens common est le génie de l'humanité_." Common-sense, which is here put forward as the genius of humanity, must be examined first of all in the way it shows itself. If we inquire the purpose to which humanity puts it, we find as follows: Humanity is conditioned by needs. If they are not satisfied, men become impatient; and if they are, it seems not to affect them. The normal man moves between these two states, and he applies his understanding--his so-called common sense--to the satisfaction of his needs. When his needs are satisfied, his task is to fill up the waste spaces of indifference. Here, too, he is successful, if his needs are confined to what is nearest and most necessary. But if they rise and pass beyond the sphere of ordinary wants, common-sense is no longer sufficient; it is a genius no more, and humanity enters on the region of error. There is no piece of foolishness but it can be corrected by intelligence or accident; no piece of wisdom but it can miscarry by lack of intelligence or by accident. Justice insists on obligation, law on decorum. Justice weighs and decides, law superintends and orders. Justice refers to the individual, law to society. The history of knowledge is a great fugue in which the voices of the nations one after the other emerge. If a man is to achieve all that is asked of him, he must take himself for more than he is, and as long as he does not carry it to an absurd length, we willingly put up with it. People whip curds to see if they cannot make cream of them. Wisdom lies only in truth. When I err, every one can see it; but not when I lie. Before the storm breaks, the dust rises violently for the last time--the dust that is soon to be laid for ever. Men do not come to know one another easily, even with the best will and the best purpose. And then ill-will comes in and distorts everything. In the world the point is, not to know men, but at any given moment to be cleverer than the man who stands before you. You can prove this at every fair and from every charlatan.