One of the many issues the Buddha refused to speculate on was the existence or significance of gods. As a Hindu he naturally learned the traditional stories of the divinities. As a man of his time, with all its religious and intellectual ferment, the Buddha questioned the wisdom of reliance on ritual sacrifice. He did not deny the existence of the gods. He merely insisted that whatever power the gods might possess, it could not solve the fundamental human dilemma. That remained the sole responsibility of the individual person. Many Buddhist sacred texts talk of the gods in mythic terms. It was, for example, the gods who made sure young Siddhartha Gautama encountered the Four Passing Sights that turned his life around. But classical Buddhist teaching does not refer to an Ultimate Reality in personal terms. That changed as popular devotional forms of Buddhism developed, especially in China, Korea, and Japan. Buddha himself assumed virtually divine proportions, and the concept of the universal Buddha-nature superseded that of the Buddha as historical human teacher. Gods of ancient Hindu myth retained a place in the Buddhist spiritual cosmos but remained very much in the background.