But to eliminate the value of _x_ is what troubles them. Herbert Spencer has tried his hand at it, but failed to express life under any higher correlation than "molecular force;" nor can he definitely inform us whether either force is third or fourth cousin to the other. But he manifestly regards their relationship as constituting either a very attractive or highly repulsive force. In his vexation at not finding the value of _x_, he is driven from mathematical to mechanical biology, and gives us this new definitional value of life--that singularly contumacious quantity which so persistently refuses to be eliminated in scientific equations: "Life is molecular machinery worked by molecular force." But as Professor Beale has utterly demoralized, if not demolished, this machinery, in his recent treatise on "The Mystery of Life," we will spare it any further blows, and proceed to the consideration of "molecular force." Before we proceed however, to the consideration of this force, let us definitely understand the meaning of the terms we shall be called upon to use. We can have no difficulty in understanding the meaning of "molecular attraction," or that force acting immediately on the integrant molecules or particles of a body, as distinguished from the attraction of gravitation which acts at unlimited distances. But when it comes to ascribing other and higher manifestations of power to molecules, such as have not been scientifically shown to exist, we must feel our way with caution, and demand of these pretentious molecules, or rather of their materialistic backers, a reason for the faith, or rather force, that is in them.