De Arte Mentis Collendi
Now concerning the first Foundation of thy Mind I will say somewhat. Thou shalt study with Diligence in the mathematics, because thereby shall be revealed unto thee the Laws of thine own Reason and the Limitations thereof. This Science manifesteth unto thee thy true Nature in respect of the Machinery whereby it worketh; and showeth in pure Nakedness, without Clothing of Personality or Desire, the Anatomy of thy conscious Self. Furthermore, by this thou mayst understand the Essence between the Relation of all Things, and the Nature of Necessity, and come to the Knowledge of Form. For this Mathematics is as it were the last Veil before the Image of Truth, so that there is no Way better than our Holy Qabalah, which analyseth all Things soever, and reduceth them to pure Number; and thus their Natures being no longer coloured and confused, they may be regulated and formulated in Simplicity by the Operation of Pure Reason, to thy great Comfort in the Work of our Transcendental Art, whereby the Many become One.
 On the Art of Training the Mind, (1) Mathematics