Many men fall from doubt and suspicion. A class of people say, "God does not need our worship and services, and has no concern with our virtues and vices: why should we restrain ourselves?" Such a doubt arises from sheer ignorance, and supposes that the Law enjoins duties for the sake of God. No. Duties are for the sake of man alone.... An ignorant man of this sort fitly compares with a patient who, being prescribed a certain treatment by his physician, does not follow it, and says that his abstinence does no harm to the physician. He speaks truly enough, but works his own destruction. The physician did not prescribe to please himself, but to cure him.

A second class of men transgress the Law and depend on the Divine Mercy. God is both merciful and a chastiser. We find that there are many distressed and poor men in this world in spite of His Mercy and His mountains of Treasure, that not a single grain of wheat grows without laborious cultivation, and that no man can be healthy without food, water and medicine. As He has ordained means for health and wealth without which they cannot be had, such is the case in the moral sphere also. Denial and ignorance are poisons to the soul, and idleness its disease. The antidotes for the poisons are knowledge and wisdom alone. The remedies for the disease are prayers and worship alone. He who takes poison while depending on the Divine Mercy, kills himself. The disease of the heart consists in desires. He who does not restrain his desires risks his life if he knows them as sinful. But if he does not regard them as harmful he has no life to risk, since he is already dead. For such disregard is denial, and denial poisons faith.

A third set would understand by self-discipline, as imposed by the Law, complete freedom from lust, anger and other evils. When they fail after practising self-discipline for a length of time, they regard the task as impossible. "Man, as he is constituted, cannot be pure, just as a black blanket cannot turn into a white one. Why should we undertake an impossible feat?" (So they think).—It is ignorance and vanity to suppose that the Law enjoins complete freedom from lust and other impulses inherent in human nature. The Prophet has said, "I am a man, and may be angry," and signs of anger were at times visible in him. God praises one who controls anger, not one who is devoid of anger. Again, the prophet had nine wives, and a man destitute of the sexual desire should be medically treated. The Prophet has countenanced the begetting of progeny and the perpetuation of the race. But he has instructed that the two (lust and anger) should be subdued so as to be under the control of the Law, as a horse under the control of the rider, or a dog under the control of the hunter. The animals should be trained, else they will set upon and overthrow the man. Lust and anger are like the dog and the horse, and it is impossible to catch the heavenly Game without them. But they should be under control, else they will destroy us. In short, the object of self-discipline is to break and subdue these impulses, and this is possible.

A fourth set proudly declare that everything is according to the Divine Will. What is the use of exertion?—When the Prophet spoke of the Divine Will, his companions said, "We shall depend upon it and refrain from exertion." The Prophet replied, "Ye shall exert, and [then] what has been ordained will be given." Thus, man should not refrain from exertion. If he has in the beginning been ordained to a noble destiny, he will attain to it [by exertion]. Good and evil destinies hinge upon virtue and vice, in the same way as health and death upon food and starvation.—Letter 18.