De Arte Kabbalistika
Do thou study most constantly, my Son, in the Art of the Holy Qabalah. Know that herein the Relations between Numbers, though they be mighty in Power and prodigal of Knowledge, are but lesser Things. For the Work is to reduce all other conceptions to these of Number, because thus thou wilt lay bare the very Structure of thy Mind, whose rule is Necessity rather than Prejudice. Not until the Universe is thus laid naked before thee canst thou truly anatomize it. The Tendencies of thy Mind lie deeper far than any Thought, for they are the Conditions and the Laws of Thought; and it is these that thou must bring to Nought.
This Way is most sure; most sacred; and the Enemies thereof most awful, most sublime. It is for the Great Souls to enter on this Rigour and Austerity. To them the Gods themselves do Homage; for it is the Way of Utmost Purity.
 On the Art of the Qabalah