"There was a whole movement surrounding the Buddha, often referred to as the Sramana movement, characterized by the investigation of the human condition using various experiential methods. Many of these methods were certainly psychological, and we might even call some of them scientific. Rebelling against an orthodox intelligentsia that relied on revealed scriptural authority to guide a ritual communication with external deities, the Sramanas, or Wanderers, were more apt to use yoga, asceticism, and meditation to access an internal landscape and gain personal insights into the nature of their own minds and bodies. Their methods of inquiry constituted a body of shared praxis, and the experiences accessed and insights gained were largely repeatable and verifiable. Thus the tradition went beyond the contributions of a few individuals, and built up profundity and authority over many generations. The Buddha was both an heir to this psychologically investigative tradition and one of its greatest contributors."
Andrew Olendzki: "Buddhist Psychology", Chapter 1, from:
Seth Robert Segall ed. "Encountering Buddhism: Western Psychology and Buddhist Teachings", SUNY Press, 2003.