The practice of sexual transmutation as couple (male-female), a technique known in Tantra and Alchemy. Arcanum refers to a hidden truth or law. A.Z.F. stands for A (agua, water), Z (azufre, sulfur), F (fuego, fire), and is thus: water + fire = consciousness. . Also, A (azoth = chemical element that refers to fire). A & Z are the first and last letters of the alphabet thus referring to the Alpha & Omega (beginning & end).
"By rejection, samsara is not left behind; it is freed within itself by letting be. Your attempts to cure your miseries have brought no ease; you are at ease by letting be. You find no happiness from craving; only when you have let go of craving."
- Padmasambhava, Advice on How to Practice the Profound Instructions