The conceptions from which he had evolved his faith were already accepted to some extent by those among whom he came. He taught that there were two spirits--Ormuzd or Good, embodying all truth, life, beauty, order, light; and Ahriman, or Evil, including all darkness, death, falsity and disorder. Life was a struggle between these two contending forces. "He laid before his people their own thoughts in all the pure transparency of crystal waters cleared from muddiness and unwholesome admixtures in the filter of his own transcendent and searching mind. He guided their groping hands, and made them grasp the truth for which they were blindly reaching. Such is the mission of every true prophet. Had the people not been ripe for his teaching, he could not have secured a hearing, or made himself understood; the people, on the other hand, could never have worked out unaided the ideal to which they were vaguely and only half-consciously drawn. They listened and understood, and were won, because, to use the expression of a great writer, they had in themselves the seed of the thoughts which the prophet expounded to them."[2] Seven times divine beings brought messages to Zoroaster. "They inculcate the doctrine of purity of body as well as of soul; they enjoin the care of useful animals, especially the cow and the dog; they emphasize the necessity of keeping the earth, the fire and the water undefiled; and from several of their ordinances we can see that Zoroaster was a civil reformer as well as a spiritual guide. Foremost among the commandments is the abhorrence of falsehood, the universal obligation to speak the truth. This is one of the most fundamental of the ethical tenets which form the basis of the entire ancient Persian religious system."[3] The writings which contained the teachings of Zoroaster are commonly known as the Zenda-Vesta. The name is misleading however, and should read Avesta-u-Zend, which translated means: "Law and Commentary." Among students the compilation is generally called the Avesta. Even a casual reading of the Old Testament reveals the fact that the various books composing it were written by different writers, writing under radically different circumstances, and at widely distant periods. The same is true of the Avesta. One of its books was probably written either by Zoroaster himself or under his supervision. This is the Gathas, or book of songs, and is the most ancient portion of the entire collection. Sermons, prayers, and sayings are therein contained, some of which possess poetic beauty and rare purity. Other books were added from time to time, until the Avesta is said to have been made up of twenty-one books, and to have covered 1,200 cowhides.