The distinction between monism and emanationism appears as early as the oldest Upanishads.  A full-fledged statement of emanationism occurs as early as the Chandogya Upanishad, which says

"3....understand that this (body) is an offshoot which has sprung up, for it could not be without a root.
   4. And what else could its root be than food?  And in the same manner, my dear, with food as an offshoot, seek for  water as the root; with water, my dear, as an offshoot seek  for heat as the root; with heat, my dear, as an offshoot,  seek for Being as its root.  All these creatures, my dear,  have their root in Being.  They have Being as their abode,  Being as their support."
[Transl. S. Radhakrishnan, The Principle Upanishads, p.457]

 (As a literary device, the teaching is presented in the form of a conversation between the sage Uddalaka Aruni and his son Shwetaketu; hence the frequent "my dear"s in the above passage)

Here one traces back the origin of being from its manifestation to its root, and in each case the root of the preceeding stage becomes the result or "offshoot" of the next stage up.  Instead of a single simple creation, as in, say, the Judeao-Christian idea of a God who creates the world all at once out of nothing, there is a repeated process of formation from the more subtle to the more gross.

back to Upanishads page
The Early Upanishads - Monistic Mysticism
The Taittiriya Upanishad
Emanationism In The Hindu Religions