beginning and the end of the aim of all noble art, we have, in the ancient art, by perception; and we have _not_, in the newer art, by knowledge. Giotto gives it us, Orcagna gives it us. Angelico, Memmi, Pisano, it matters not who,--all simple and unlearned men, in their measure and manner,--give it us; and the learned men that followed them give it us not, and we, in our supreme learning, own ourselves at this day farther from it than ever. § XXIV. "Nay," but it is still answered, "this is because we have not yet brought our knowledge into right use, but have been seeking to accumulate it, rather than to apply it wisely to the ends of art. Let us now do this, and we may achieve all that was done by that elder ignorant art, and infinitely more." No, not so; for as soon as we try to put our knowledge to good use, we shall find that we have much more than we can use, and that what more we have is an encumbrance. All our errors in this respect arise from a gross misconception as to the true nature of knowledge itself. We talk of learned and ignorant men, as if there were a certain quantity of knowledge, which to possess was to be learned, and which not to possess was to be ignorant; instead of considering that knowledge is infinite, and that the man most learned in human estimation is just as far from knowing anything as he ought to know it, as the unlettered peasant. Men are merely on a lower or higher stage of an eminence, whose summit is God's throne, infinitely above all; and there is just as much reason for the wisest as for the simplest man being discontented with his position, as respects the real quantity of knowledge he possesses. And, for both of them, the only true reasons for contentment with the sum of knowledge they possess are these: that it is the kind of knowledge they need for their duty and happiness in life; that all they have is tested and certain, so far as it is in their power; that all they have is well in order, and within reach when they need it; that it has not cost too much time in the getting; that none of it, once got, has been lost; and that there is not too much to be easily taken care of. § XXV. Consider these requirements a little, and the evils that result in our education and polity from neglecting them. Knowledge is mental food, and is exactly to the spirit what food is to the body (except that the spirit needs several sorts of food, of which knowledge is only one), and it is liable to the same kind of misuses. It may be mixed and disguised by art, till it becomes unwholesome; it may be refined, sweetened, and made palatable, until it has lost all its power of nourishment; and, even of its best kind, it may be eaten to surfeiting, and minister to disease and death.