“The medieval theologian Peter Lombard provided a definition of sacramentum that is still often cited by Catholics today: ‘an outward sign of inward grace.’ Since Thelemites accept neither grace nor guilt as the basis for interaction with the divine, it is evident that at a minimum this definition would need to be altered for our purposes to reflect a signification of ‘will’ rather than ‘grace.’ But even then, the relationship between ‘outward’ and ‘inward’ is suspect on such grounds as CCXX I:8. Thomas Aquinas’ definition of sacrament as ‘the sign of a sacred thing in so far as it sanctifies men,’ may perhaps be of use, as long as it is understood that the condition of sanctification in Thelemic Gnosis differs considerably from that found in the slave-religion Christianity.
Certainly, we do not make the sacramental status of a practice dependent on its institution by Aleister Crowley, any more than we do by Jesus of Nazareth. While Crowley’s precedent may lead us to consider certain practices as sacraments (and to define the regular form of those practices); it is in no way a necessary ingredient for those sacraments which are demanded by the vital circumstances of the Church or its members.”
(via Vigorous Food & Divine Madness)