The terms Obeah and Wanga are African diasporic words that occur in The Book of the Law (the sacred text of Thelema, written by English author and occultist Aleister Crowley in 1904):
Also the mantras and spells; the obeah and the wanga; the work of the wand and the work of the sword; these he shall learn and teach. (AL I:37).
Obeah is a folk religion and folk magic found among those of African descent in the West Indies. It is derived from West African Igbo sources and has a close North American parallel in African American conjure or hoodoo.
A wanga (sometimes spelled oanga or wanger) is a magical charm packet found in the folk magic practices of Haiti, and as such it is connected to the West African religion of Vodun, which in turn derives from the Fon people of what is now Benin.
In his Commentaries, Crowley explains:
The obeah is the magick of the Secret Light with special reference to acts; the wanga is the verbal or mental correspondence of the same. [...] The "obeah" being the acts, and the "wanga" the words, proper to Magick, the two cover the whole world of external expression.
It is possible that Crowley was not referring to literal Jamaica Obeah practices or to actual wanga.
He goes on to say:
Magick is the management of all we say and do, so that the effect is to change that part of our environment which dissatisfies us, until it does so no longer. We "remould it nearer to the heart's desire."
Magick ceremonies proper are merely organized and concentrated attempts to impose our Will on certain parts of the Cosmos. They are only particular cases of the general law.
But all we say and do, however casually, adds up to more, far more, than our most strenuous Operations. "Take care of the pence, and the pounds will take care of themselves." Your daily drippings fill a bigger bucket than your geysers of magical effort. [...]
List of magical terms and traditions
Thelemapedia. (2004). Obeah and Wanga. Retrieved April 16, 2006.
Crowley, Aleister. (1996). The Law is for All Tempe, Arizona: New Falcon Publications.
____. (1979). The Confessions of Aleister Crowley London;Boston: Routledge and Kegan Paul.