While we thus commend illustrations for necessary uses, it must be remembered that they are not the strength of a sermon any more than a window is the strength of a house; and for this reason, among others, _they should not be too numerous_. Too many openings for light may seriously detract from the stability of a building. We have known sermons so full of metaphors that they became weak, and we had almost said _crazy_, structures. Sermons must not be nosegays of flowers, but sheaves of wheat. Very beautiful sermons are generally very useless ones. To aim at elegance is to court failure. It is possible to have too much of a good thing: a glass house is not the most comfortable of abodes, and besides other objectionable qualities it has the great fault of being sadly tempting to stone-throwers. When a critical adversary attacks our metaphors he generally makes short work of them. To friendly minds images are arguments, but to opponents they are opportunities for attack; the enemy climbs up by the window. Comparisons are swords with two edges which cut both ways; and frequently what seems a sharp and telling illustration may be wittily turned against you, so as to cause a laugh at your expense: therefore do not rely upon your metaphors and parables. Even a second-rate man may defend himself from a superior mind if he can dexterously turn his assailant's gun upon himself. Here is an instance which concerns myself, and I give it for that reason, since these lectures have all along been autobiographical. I give a cutting from one of our religious papers: "Mr. Beecher was neatly tripped up in 'The Sword and the Trowel.' In his 'Lectures on Preaching' he asserts that Mr. Spurgeon has succeeded 'in spite of his Calvinism'; adding the remark that 'the camel does not travel any better, nor is it any more useful, because of the hump on its back.' The illustration is not a felicitous one, for Mr. Spurgeon thus retorts: 'Naturalists assure us the camel's hump is of great importance in the eyes of the Arabs, who judge of the condition of their beasts by the size, shape, and firmness of their humps. The camel feeds upon his hump when he traverses the wilderness, so that in proportion as the animal travels over the sandy wastes, and suffers from privation and fatigue, the mass diminishes; and he is not fit for a long journey till the hump has regained its proportions. Calvinism, then, is the spiritual meat which enables a man to labor on in the ways of Christian service; and, though ridiculed as a hump by those who are only lookers-on, those who traverse the weary paths of a wilderness experience know too well its value to be willing to part with it, even if a Beecher's splendid talents could be given in exchange.'"