The Third and Last Book of Magick, or Occult Philosophy - Henry Cornelius Agrippa. Now it is time to turn our pen to higher matters, and to that part of magick which teacheth us to know and perfectly understand the rules of religion, and how we ought to obtain the truth by divine religion, and how rightly to prepare our mind and spirit. By which only we can comprehend the truth. For it is a common opinion of the magicians that unless the mind and spirit be in good case, the body cannot be in good health.
But then a man can be truly sound when body and soul are so coupled, and agree together, that the firmness of the mind and spirit are not inferior to the powers of the bod, but a firm and stout mind (saith Hermes) that we not otherwise obtain than by integrity of life, by piety, and last of all, by divine religion. For holy religion purgeth the mind, and maketh it divine, it helpeth nature, and strengtheneth natural powers, as a phycisian helpeth the health of the body, and a husbandman the strength of the earth. Whosoever therefore, religion being laid aside, do consider only in natural things, is wont very oft to be deceived by evill spirits. But from the knowledge of religion, the contempt and cure of vices ariseth, and a safeguard against evil spirits.
To conclude, nothing is more pleasant and acceptable to God than a man perfectly pious, and truly religious, who so far excelleth other men, as he himself is distant from the immortal gods.
