Magick is not capable of producing miracles or violating the physical laws of the universe (i.e., it cannot cause a solar eclipse), although "it is theoretically possible to cause in any object any change of which that object is capable by nature", according to Crowley. Crowley got the inspiration for the spelling from its usage by the famous English magician John Dee. His definition treats magic in the context of the paranormal and magic in the context of religion as special cases.

Crowley defined magick as "the science and art of causing change to occur in conformity with the will". By this, he included "mundane" acts of will as well as ritual magic. In Magick in Theory and Practice, Chapter XIV, Crowley says:

What is a Magical Operation? It may be defined as any event in nature which is brought to pass by Will. We must not exclude potato-growing or banking from our definition. Let us take a very simple example of a Magical Act: that of a man blowing his nose. [1]

Some in the Neopagan and occult communities have amended this definition, using the word "magick" exclusively in a paranormal sense. However, Crowley still wields significant influence in these circles.

Concentration or meditation plays an important role in Crowley's system. A certain amount of restricting the mind to some imagined object, according to this theory, produces mystical attainment or "an occurrence in the brain characterized essentially by the uniting of subject and object". (Book Four, Part 1: Mysticism.)

Magick, as defined previously, seeks to aid concentration by constantly recalling the attention to the chosen object (or Will), thereby producing said attainment. For example, if one wishes to concentrate on a god, one might memorize a system of correspondences (perhaps chosen arbitrarily, as this would not affect its usefulness for mystical purposes) and then make every object that one sees "correspond" to said god.

Aleister Crowley wrote:

Now what is all this but to do in a partial (and if I may say so, romantic) way what the Yogi does in his more scientifically complete yet more austerely difficult methods? And here the advantage of Magick is that the process of initiation is spontaneous and, so to speak, automatic. You may begin in the most modest way with the evocation of some simple elemental spirit; but in the course of the operation you are compelled, in order to attain success, to deal with higher entities. Your ambition grows, like every other organism, by what it feeds on. You are very soon led to the Great Work itself; you are led to aspire to the Knowledge and Conversation of the Holy Guardian Angel, and this ambition in turn arouses automatically further difficulties the conquest of which confers new powers. In the Book of the Thirty Aethyrs, commonly called "The Vision and the Voice", it becomes progressively difficult to penetrate each Aethyr. In fact, the penetration was only attained by the initiations which were conferred by the Angel of each Aethyr in its turn. There was this further identification with Yoga practices recorded in this book. At times the concentration necessary to dwell in the Aethyr became so intense that definitely Samadhic results were obtained. We see then that the exaltation of the mind by means of magical practices leads (as one may say, in spite of itself) to the same results as occur in straightforward Yoga. --(Crowley, Yoga for Yellowbellies)

Crowley also made claims for the paranormal effects of magick. However, he defined any attempt to use this power for a purpose other than aiding attainment as "black magic".

Sex Magick

This branch of magick takes many forms but always involves a preparation of a proper and sacred atmosphere (as with other magick), pre-cleansing of the body and mind, banishment of evil prior to beginning the ritual, focusing upon the ritual/outcome, climax, post-ritual celebration and giving thanks and praise to the goddess and god figures.

Sex magick can be practiced solo, as a couple or as a group. One particularly interesting form of ritualistic sex magick is based upon the polyandry concept of one female having sexual relations with two or more males during a single ritual and allowing their semen to mix within her body. The conceptual basis for this ritual is that semen is believed by many to be a most powerful magickal fluid. When mixed with the semen of others, its power increases exponentially.

In some quarters, it is believed that this form of magick works through the powerful release of psychic energy at the moment of orgasm. The magus deliberately prolongs the arousal phase and delays orgasm for as long as possible. When the orgasm occurs, it is accompanied by intense visualisation of the desired outcome.

One of the popular methods for working sex magick is as follows:

Relax your mind and body using any suitable relaxation technique.
Use erotica or a partner to attain sexual arousal.
Hold or intensify this state of arousal for a prolonged period of time (30 to 60 minutes).
Without losing the erection/arousal, visualise the desired outcome of your magickal working (the erection/arousal can be retained through manual stimulation either by yourself or by your partner).
Have an orgasm.
As your body goes into a state of post-orgasmic relaxation, express (either mentally or aloud) your heartfelt gratitude for the fulfilment of your wish/desire.

The process described above is very similar to the methods advocated and used by Aleister Crowley.

Aleister Crowley makes some commentaries on Atu XV in The Book of Thoth relating to sex magick and the eye of Ra/Horus/Shiva:

"There is a special technical magical meaning, which is explained openly only to initiates of the Eleventh degree of the O.T.O.; a grade so secret that it is not even listed in the official documents. It is not even to be understood by study of the Eye in Atu XV[The Tower of Thoth Tarot]. Perhaps it is lawful to mention that the Arab sages and the Persian poets have written, not always guardedly, on the subject."

Books on Sex Magick by Aleister Crowley

• Liber IAO, Aleister Crowley, Aleister Crowley
• IAO. Sexual Magick. Gives three methods of attainment through a willed series of thoughts. The active form of Liber CCCXLV.
• De Nuptis Secretis Deorum Cum Hominibus, Aleister Crowley
• Liber Stellae Rubeae, Aleister Crowley [Download in HTML]
• A secret ritual of Apep, the heart of IAO-OAI, delivered unto V.V.V.V.V. for his use in a certain matter of Liber Legis. Sexual Magick veiled in symbolism.
• Agape, Azoth, Aleister Crowley
• The Book of the Unveiling of the Sangraal wherein it is spoken of the Wine of the Sabbath of the Adepts. Secrets instructions of the IX° O.T.O. (Sex Magick.)
• Liber Cheth vel Vallum Abiegni, Aleister Crowley
  A perfect account of the task of the Exempt Adept considered under the Symbols of a particular plane, not the intellectual. Sexual magick veiled in symbolism.
• Liber A'ash vel Capricorni Pneumatici, Aleister Crowley,
  Analyzes the nature of the creative magickal force in man, explains how to awaken it, how to use it and indicates the general as well as the particular objects to be gained thereby. Sexual magick heavily veiled in symbolism.
• Paris Working, The (including Esoteric record and sundrys), Aleister Crowley
• A record of homosexual magick operations.