Radiation is a term used by H. P. Blavatsky in her writings in relation to the process of re-awakening of the universe. The term is sometimes used as a synonym of emanation although strictly speaking they are different:
Q. How do the terms “Radiation” and “Emanation” differ in the Secret Doctrine?
A. They express, to my mind, two entirely different ideas, and are the best apologies for the original terms that could be found; but if the ordinary meanings are attached to them the idea will be missed. Radiation is, so to say, the unconscious and spontaneous shooting forth, the action of a something from which this act takes place; but emanation is something from which another thing issues in a constant efflux, and emanates consciously. An orthodox Occultist goes so far as to say that the smell of a flower emanates from it “consciously”—absurd as it may seem to the profane. Radiation can come from the Absolute; Emanation cannot. One difference exists in the idea that Radiation is sure, sooner or later, to be withdrawn again while Emanation runs into other emanations and is thoroughly separated and differentiated. Of course at the end of the cycle of time emanation will also be withdrawn into the One Absolute; but meanwhile, during the entire cycle of changes emanation will persist. One thing emanates from the other, and, in fact, from one point of view, emanation is equivalent to Evolution; while “radiation” represents to my mind—in the pre-cosmic period, of course—an instantaneous action like that of a piece of paper set on fire under a burning glass, of which act the Sun knows nothing. Both terms, of course, are used for want of better.
- Helena Petrovna Blavatsky, Collected Writings vol. X (Adyar, Madras: Theosophical Publishing House, 1964), 359.