In short, the teachers of the Upanishads not only do not declare clearly what they believed in regard to cosmogonic and eschatological matters, but many of them probably did not know clearly what they believed. Their great discovery was that man's spirit was not particular and mortal, but part of the immortal universal. Whether this universal was a being alive and a personal _[=a]tm[=a]_, or whether this personal being was but a transient form of impersonal, imperishable being;[31] and whether the union with being, _brahma_, would result in a survival of individual consciousness,--these are evidently points they were not agreed upon, and, in all probability, no one of the sages was certain in regard to them. Crass identifications of the vital principle with breath, as one with ether, which is twice emphasized as one of the two immortal things, were provisionally accepted. Then breath and immortal spirit were made one. Matter had energy from the beginning, _brahma_; or was chaos, _asat_, without being. But when _asat_ becomes _sat_, that _sat_ becomes _brahma_, energized being, and to _asat_ there is no return. In eschatology the real (spirit, or self) part of man (ego) either rejoices forever as a conscious part of the conscious world-self, or exists immortal in _brahma_--imperishable being, conceived as more or less conscious.[32] The teachers recognize the limitations of understanding: "The gods are in Indra, Indra is in the Father-god, the Father-god (the Spirit) is in _brahma_"--"But in what is _brahma?_" And the answer is, "Ask not too much" (_Brihad. [=A]ran. Up_. 3. 6). These problems will be those of the future formal philosophy. Even the Upanishads do not furnish a philosophy altogether new. Their doctrine of _karma_ their identification of particular ego and universal ego, is not original. The 'breaths,' the 'nine doors,' the 'three qualities,' the _purusha_ as identical with ego, are older even than the Br[=a]hmanas (Scherman, _loc. cit_. p. 62).