According to some scholars, the philosophical outlook of earliest Buddhism was primarily negative, in the sense that it focused on what doctrines to "reject" more than on what doctrines to "accept". Only knowledge that is useful in attaining liberation is valued. According to this theory, the cycle of philosophical upheavals that in part drove the diversification of Buddhism into its many schools and sects only began once Buddhists began attempting to make explicit the implicit philosophy of the Buddha and the early texts.