Involution means the Descent of Spirit into Matter, specifically of the Infinite Universal Consciousness into finite self-delimited form, although the term could be used in a more limited sense as well.

I would define four different types of Involution, each with their mirror opposite.  That opposite can better be called de-involution or un-involution, as it is not the same as evolution.  Together with abiding in the Supreme and manifesting in embodied form this makes a cycle, the Brahmachakra ("wheel of Brahma") of Hinduism.  This gives the following diagram,

Source Absolute Reality
Descent Emanation Incarnation	Ascent withdrawal re-absorption
incarnation maintenance of the world-process Change Transformation Metamorphosis

So we have at least four pairs of modes of descent/ascent, four variations on the above diagram.

This is the central thesis of Neoplatonism and associated metaphysical systems (Middle Platonism, Neopythagoreanism, etc).  It was also adopted, perhaps via Neoplatonism, in Islamic Esotericism and in Kabbalah.  It is also found in the concept of Panchakritya or the Five Acts of Shiva (the Godhead) in Kashmir Shaivism (a slightly similiar (but less specific) three-fold scheme was developed in Neoplatonism) and in Taoism.

Emanation can be represented by the following diagram:

	Sequence
Manifestation	A	A	A	A
		B	B	B
			C	C
				D

A generates B burt is not deminished thereby.  B likewise generates C and so on.

Re-absorption or withdrawl is of course the reverse.  D is absorbed back into C, C into B, and B into A.

Involution