Thelema is a Greek word for willpower.
The real Adept is called a Thelemite, and all those Adepts like Jesus, Moses, Hermes and Krishna are Thelemites.
It is this willpower (Thelema) that is the power that we need to exercise in order to achieve the Self-realization of the Being. (Enlightenment)
To understand this is very important, because the whole great work relies on willpower, on Thelema.
Question: What can you say about the phrase ‘Do what thou wilt’ and the very prominent idea that Aleister Crowley is the main teacher of Thelema?
Answer: Well, Aleister Crowley just degenerated and inverted the doctrine. ‘Do what thou wilt’ – well obviously the demons do what they wilt but it is inverted.
If you do your own ‘Wilt’, who are ‘you’? Right?
If you think you are the ego, then you will end up like Aleister Crowley, a sick, twisted, perverted drug addict. He had an inverted will, a ‘Demonius est deus inversus,’ meaning that his own will was going down.
He said it himself when he claimed his name is ‘The Beast 666’ (which is the pure ego.)
But ‘Do what thou wilt’ in Thelema, in the right way, is to do the Will of God. To slay the proverbial dragons, and align our will with the angelic hierarchy.
Obviously, Aleister Crowley developed evil will, his own inverted Thelema.
In order to develop good will, you have to annihilate the evil will within, and that is ego, desire, lust, hatred, greed, etc.
You must develop this good will not only on the Physical Plane, but in the Astral Plane, in the Mental Plane, Causal Plane, Buddhic Plane, Spiritual Plane and higher levels until you become a paramartasattya; a truly enlightened being.