 In the classical period of Arabic and Islamic thought (9th–12th centuries), original and influential accounts of causation emerged from debate within two intellectual traditions: speculative theology (kalām) and Greek philosophy (falsafah). Among the theologians (mutakallimūn), dispute about the distribution of agency and causal power played a role in the interpretation of revealed accounts of God and his relationship to the world. By contrast, the philosophers (falāsifah) saw themselves as developing a rationalist science begun by Aristotle. In this tradition, to know a thing is to know its causes. Discovery of the nature of causation is regarded as fundamental to science.