That storm reached a head in Buddhism, but its premonitory signs appear in the Upanishads, and its first outbreak preceded the advent of Gautama.  Were it possible to draw a line of demarcation between the Upanishads that come before and after Buddhism, it would be historically more correct to review the two great schisms, Jainism and Buddhism, before referring to the sectarian Upanishads.  For these latter in their present form are posterior to the rise of the two great heresies.  But, since such a division is practically uncertain in its application, we have thought it better in our sketch of the Upanishads and legal literature to follow to the end the course of that agitated thought, which, starting with the great identification of jiva, the individual spirit, and [=a]tm[=a], the world-spirit, the All, continues till it loses itself in a multiplication of sectarian dogmas, where the All becomes the god that has been elected by one communion of devotees.[2]

The external characteristics of Upanishad thought are those of a religion that has replaced formal acts by formal introspection.  The Yogin devotee, who by mystic communion desires absorption into the world-spirit, replaces the Sanny[=a]sin and Yati ascetics, who would accomplish the same end by renunciation and severe self-mortification.  This is a fresh figure on the stage of thought, where before were mad Munis, beggars, and miracle-mongers.  On this stage stands beside the ascetic the theoretical theosophist who has succeeded in identifying himself, soberly, not in frenzy, with God.[3] What were the practical results of this teaching has been indicated in part already.  The futility of the stereotyped religious offices was recognized.  But these offices could not be discarded by the orthodox.  With the lame and illogical excuse that they were useful as discipline, though unessential in reality, they were retained by the Brahman priest.  Not so by the Jain; still less so by the Buddhist.

In the era in which arose the public revolt against the dogmatic teaching of the Brahman there were more sects than one that have now passed away forgotten.  The eastern part of India, to which appertain the later part of the Catapatha Br[=a]hmana and the schismatic heresies, was full of religious and philosophical controversy.  The great heretics were not innovators in heresy.  The Brahmans permitted, encouraged, and shared in theoretical controversy.  There was nothing in the tenets of Jainism or of Buddhism that from a philosophical point of view need have caused a rupture with the Brahmans.