Thelema is Greek for "will".  It is a skeptical, magickal and scientific philosophy which proposes that we have incarnated to love, i.e. that we have divided from the Infinite for the sake of uniting with all possible combinations of experience, as per our True Will, which we may discover and consciously enact.  It proposes that the culture and schemas of humankind evolve, and that as of about a century ago we have essentially transcended both patriarchy and matriarchy.  Now...
  

Every man and every woman is a star.

THE BOOK OF THE LAW
Cap. I, verse 3

 
The old pagan worship of the Mother-idea was superseded by the word IAO or its equivalents, which asserted the formula of the Dying God, and made the Male, dying to himself in the act of love, the engineer of the continued life of the race.  This revolution cut at the root of all previous custom.  Matriarchy vanished; self-sacrifice became the cardinal virtue, and so through infinite ramifications.

This idea of accomplishing the Great Work by a voluntary death was bound up with the belief that the sun died, and was reborn with the hours and the seasons.  Astronomy having exploded this fiction, mankind was ready to gain a further comprehension of its own parallel case.

My own word, Thelema, supplies a new and scientifically sound basis for ethics.  Self-sacrifice is a romantic folly; death does not end life; it is a temporary phase of life as night and winter are of terrestrial activity.  Many other conceptions are implied in this word, Thelema.  In particular, each individual is conceived as the centre of his own universe, his essential nature determining his relations with similar beings and his proper course of action.  It is obvious that these ideas are revolutionary.  Yet to oppose them is to blaspheme science.  Already, in a thousand ways, the principles involved have replaced those of the Dying God.  Little remains but to accept Thelema consciously as a statement of law, so that any given problem may be solved by applying it to each case.

ALEISTER CROWLEY
Confessions, Cap. 81

 
Do what thou wilt shall be the whole of the Law....

Love is the law, love under will.

THE BOOK OF THE LAW
Cap. I, verses 40 & 57

 
 

Will is preeminently, however, not free, but true, thus raising the Law of Thelema above simple libertarianism.

ALEXANDER DUNCAN
The Law of Thelema, ReligiousTolerance.org

  
The Book of the Law
Liber AL vel Legis (The Book of the Law) subfigura CCXX is Thelema's chief holy book.

Qabalah
Crowley's writings treating Qabalah (and some to which they refer)

Aleister Crowley
The prophet of Thelema, former head of the O.T.O., and co-founder of the A.^·.A.^·..

The O.T.O.
The Ordo Templi Orientis is a paramasonic, Thelemic secret society.

The A.^·.A.^·.
The Astron Argon (a.k.a. Astrum Argenteum) is an ascetic, Thelemic secret order.

My Categorical Indices of the Equinox
The Equinox is the Official Organ of the A.^·.A.^·. (and later the O.T.O.); the Review of Scientific Illuminism.

Some useful Thelemic sites
Vere Chappell's Thelema Home Page
LAShTAL.com
Thelema.nu
Thelemapedia.org  The original open source encyclopedia of all things Thelemic.