The Argentinum Astrum "A∴A∴" is an esoteric society founded by Aleister Crowley (1875-1947) and George Cecil Jones in the year 1907.

Crowley was part of the Golden Dawn society but due to internal disputes he decided to abandon it. In 1907 taking the doctrines of the Golden Dawn and grouping several dissidents of the same founded the so-called Argentinum Astrum, "A∴A∴" ("Silver Star" in Castilian).

This new society is internally organized in the same way as the "Golden Dawn", it consists of 11 degrees divided between a preparatory stage and three internal initiatory orders.

The most internal of these three orders is the one called Astrum Argentum.

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