Mbh 3.207.1c

This whole creation, O Brahmana, is full of animal life, sustaining itself with food derived from living organisms. Dost thou not mark that fish preys upon fish, and that various species of animals prey upon other species, and there are species the members of which prey upon each other? Men, O Brahmana, while walking about hither and thither, kill numberless creatures lurking in the ground by trampling on them, and even men of wisdom and enlightenment destroy animal life in various ways, even while sleeping or reposing themselves. What hast thou to say to this?--The earth and the air all swarm with living organisms, which are unconsciously destroyed by men from mere ignorance. Is not this so? The commandment that people should not do harm to any creature, was ordained of old by men, who were ignorant of the true facts of the case. For, O Brahmana, there is not a man on the face of this earth, who is free from the sin of doing injury to creatures. After full consideration, the conclusion is irresistible that there is not a single man who is free from the sin of doing injury to animal life. Even the sage, O good Brahmana, whose vow is to do harm to no creature, doth inflict injury to animal life. Only, on account of greater needfulness, the harm is less. Men of noble birth and great qualities perpetrate wicked acts in defiance of all, of which they are not at all ashamed. Good men acting in an exemplary way are not commended by other good men; nor are bad men acting in a contrary way praised by their wicked compeers; and friends are not agreeable to friends, albeit endowed with high qualities; and foolish pedantic men cry down the virtues of their preceptors. This reversal of the natural order of things, O good Brahmana, is seen everywhere in this world. What is thy opinion as to the virtuousness or otherwise of this state of things? There is much that can be said of the goodness or badness of our actions.