of a line of thought.  In this sense it is clear that many ideas of the Sankhya appear among the Jains, but the Jains know nothing of the evolution of matter described by the Sankhya manuals and think of the relation of the soul to matter in a more materialistic way.  The notion of the separate eternal soul was the object of the Buddha’s persistent polemics and was apparently a popular doctrine when he began preaching.  The ascetic and meditative exercises prescribed by the Yoga were also known before his time and the Pitakas do not hide the fact that he received instruction from two Yogis.  But though he was acquainted with the theories and practices which grew into the Yoga and Sankhya, he did not found his religion on them for he rejected the idea of a soul which has to be delivered and did not make salvation dependent on the attainment of trances.  If there was in his time a systematic Sankhya philosophy explaining the nature of suffering and the way of release, it is strange that the Pitakas contain no criticism of it, for though to us who see these ancient sects in perspective the resemblance of Buddhism to the Sankhya is clear, there can be little doubt that the Buddha would have regarded it as a most erroneous heresy, because it proposes to attain the same objects as his own teaching but by different methods.

Sankhya ideas are not found in the oldest Upanishads, but they appear (though not in a connected form) in those of the second stratum, such as the Svetasvatara and Katha.  It therefore seems probable, though not proven, that the origin of these ideas is to be sought not in the early Brahmanic schools but in the intellectual atmosphere non-theistic, non-sacerdotal, but audaciously speculative which prevailed in the central and eastern part of northern India in the sixth century B.C.  The Sankhya recognizes no merit in sacrifices or indeed in good works of any kind, even as a preliminary discipline, and in many details is un-Brahmanic.  Unlike the Vedanta Sutras, it does not exclude Sudras from higher studies, but states that there are eight classes of gods and five of animals but only one of men.  A teacher must have himself attained emancipation, but there is no provision that he must be a Brahman.  Perhaps the fables and parables which form the basis of the fourth book of the Sankhya Sutras point to some more popular form of instruction similar to the discourses of the Buddha.  We may suppose that this ancient un-Brahmanic school took shape in several sects, especially Jainism and Buddhism, and used the Yoga discipline.  But the value and efficacy of that discipline were admitted almost universally and several centuries later it was formulated in the Sutras which bear the name of Patanjali in a shape acceptable to Brahmans, not to Buddhists.  If, as some scholars think, the Yoga sutras are not earlier than 450 A.D.[760] it seems probable that it was Buddhism which stimulated the Brahmans to codify the principles and practice of Yoga, for the Yogacara school of Buddhism