One of the primary duties of the true Buddhist is to seek knowledge, for true knowledge, insight, is the cure for desire. This knowledge which quenches all craving thirst is best attained, so Buddha taught, through meditation.[280] One must meditate on the transitoriness of life, on pain, on death, on truth, on gentleness, on love. It was through profound meditation under the Bo tree that Gautama became the Buddha, “The Enlightened.” Another cardinal virtue of the Buddhist ideal of character is universal benevolence. By no other ethical system has such stress been laid upon the duty of gentleness to everything that has life. The animal world is here brought within the sanctuary of morality and safeguarded by ethical sentiment. It is of course the doctrine of transmigration, which Buddhism inherits from Brahmanism, which gives animal ethics the prominent place it holds in Buddhist morality.[281] Still a third requirement of the true Buddhist is toleration, which follows as a corollary from the virtue of universal benevolence. In the prominent place assigned this virtue in the ideal of character, Buddhism stands alone among the great world religions. A fourth cardinal duty of the ideal is to make known to all men the eightfold way to salvation. Buddha’s command to his disciples was, “Go ye now and preach the most excellent Law, explaining every point thereof, unfolding it with diligence and care.” This is a duty which brings its own reward; for the exercise of compassion and charity produces that serenity of spirit which is the aim of moral striving; and hence nothing advances one more rapidly on the way to salvation than preaching the good tidings and laboring to lessen the sorrows and lighten the burdens of one’s fellow creatures. The moral requirement to preach to all the most excellent way made of Buddhism a missionary religion. In a few centuries after the death of Buddha devoted missionaries had spread the new faith throughout the Far East. [Sidenote: The different degrees of moral attainment] There are in Buddhism three grades of moral attainment. The lowest is that which may be reached by any one in the ordinary life. Through purity of thought and word and deed, through the exercise of universal kindliness, and by the fulfillment of every duty pertaining to his station in life, one attains such a degree of moral excellence that he may at least hope at death to avoid painful rebirth.