1. If _intensity_ be fixed upon as the standard, no one can define it, so as to tell us what he means. The command requiring us to love with _all_ the heart, if understood as requiring a certain degree of intensity of intention, may mean the highest degree of tension of which our nature is susceptible. Or it may mean the highest possible degree, consistent with our existence in this body; or the highest degree consistent with the most perfect health; or some inconceivable indefinable degree, nobody knows what. It cannot include all, and may and must mean some one of the above-named dogmas. Yet no one would dare to tell us which. Has God given, or does our own reason give us, a standard of moral judgment of which no one can form a conception, or give us a definition? 2. No one could practically apply this standard, if he could define it, as a test of moral action. The reason is obvious. No one, but Omniscience, can possibly know what degree of tensity our nature is capable of; nor precisely what degree is compatible with life, or with the most perfect health. If intensity, then, is the standard by which we are required to determine definitely the character of moral actions, we are in reality required to fix definitely the value of an unknown quantity, to wit: moral action, by a standard of which we are, and of necessity must be, most profoundly ignorant. We are required to find the definite by means of the indefinite; the plain by means of the "palpable obscure." Has God, or our own reason, placed us in such a predicament as this, in respect to the most momentous of all questions, the determination of our true moral character and deserts? 3. While the standard under consideration is, and must be, unknown to us, it is perpetually varying, and never fixed. The degree of intensity of mental effort of which we are capable at one moment, differs from that which is possible to us at another. The same holds equally of that which is compatible with life and health. Can we believe that "the judge of all the earth" requires us to conform, and holds us responsible for not conforming to a standard located we cannot possibly know where, and which is always movable, and never for a moment remaining fixed?