Definition of evolution: progressive transition from one state to another, transformation over time.
Definition of involution: regression, coiled inwards.
Evolution and involution are linked and balanced, like descent and ascent. One cannot exist without the other. But everything starting from the source, from the highest, the descent necessarily precedes the ascent, involution is therefore prior to evolution. We must first descend to incarnate, in order to be able to (re)ascend in consciousness.
The universe is governed by an identical law for all its manifestations. This law allows an infinity of modifications and variations: Creation starts from unitary principles and radiates through innumerable currents of diversity and multiformity. The principle fragments as it devolves into matter, because it comes up against its density and resistance. Then the ascent is done by reuniting.
At the top, everything is unity. Below, everything is fragmented. From the highest eternal principle to the lowest manifestation of matter, a gigantic double ladder unfolds on which beings can freely ascend or descend.
Evolution is reintegration, it is the memory of unity. It is the vibrational elevation, from duality to unity. Involution is the engine of creation, of incarnation, perpetual and multiform. It is the fall, the passage from unity towards duality.
Evolution is the reintegration of different manifested forms into a unity. Involution is from uniformity towards diversity of forms.
Evolution is an upward movement returning to the source, it is the spiritualization of matter. Involution is a spiritual regression but a necessity of material experience, it is the materialization of the Spirit.
Evolution brings together and unites. Involution divides and fragments.
Free will is: evolve or involve? Any choice results in an evolutionary or involutionary process, a rise in consciousness or a descent even lower. Like on a ladder: it is difficult and long to climb, and therefore to evolve. But it is quick and easy to descend, and therefore to involve.