With thus much understood at the outset, we can advance. But not without one more point understood as well. The arguments I am about to urge all proceed on two suppositions: first, when we make theories about the world and discuss them with one another, we do so in order to attain a conception of things which shall give us subjective satisfaction; and, second, if there be two conceptions, and the one seems to us, on the whole, more rational than the other, we are entitled to suppose that the more rational one is the truer of the two. I hope that you are all willing to make these suppositions with me; {147} for I am afraid that if there be any of you here who are not, they will find little edification in the rest of what I have to say. I cannot stop to argue the point; but I myself believe that all the magnificent achievements of mathematical and physical science--our doctrines of evolution, of uniformity of law, and the rest--proceed from our indomitable desire to cast the world into a more rational shape in our minds than the shape into which it is thrown there by the crude order of our experience. The world has shown itself, to a great extent, plastic to this demand of ours for rationality. How much farther it will show itself plastic no one can say. Our only means of finding out is to try; and I, for one, feel as free to try conceptions of moral as of mechanical or of logical rationality. If a certain formula for expressing the nature of the world violates my moral demand, I shall feel as free to throw it overboard, or at least to doubt it, as if it disappointed my demand for uniformity of sequence, for example; the one demand being, so far as I can see, quite as subjective and emotional as the other is. The principle of causality, for example,--what is it but a postulate, an empty name covering simply a demand that the sequence of events shall some day manifest a deeper kind of belonging of one thing with another than the mere arbitrary juxtaposition which now phenomenally appears? It is as much an altar to an unknown god as the one that Saint Paul found at Athens. All our scientific and philosophic ideals are altars to unknown gods. Uniformity is as much so as is free-will. If this be admitted, we can debate on even terms. But if any one pretends that while freedom and variety are, in the first instance, subjective demands, necessity and uniformity are something {148} altogether different, I do not see how we can debate at all.[3]