De Mysterio Prudentiæ
Behold now Nature, how prodigal is She of her Forces! The evident Will of every Acorn is to become an Oak; yet nigh all fail of that Will. Therefore one Secret of Magick is Œconomy of thy Force; to do no Act unless secure of its Effect. And if every Act has an Effect on every Plane, how canst thou do this unless thou be connected with all Planes? For this Reason must thou know thoroughly not only thy Body and thy Mind, but thy Body of Light and all its subtler Principles soever. But I will have thee consider most especially what Powers thou hast within thee which are certainly capable of great Effects, yet which are constantly wasted. Think then whether, if these Powers, frustrate of their End upon one Plane, might not be turned to high Purpose and assured Success upon another. For an hundred Acorns, rightly set in Conditions fit for their true Growth, will become an hundred Oaks, while otherwise they make but one Meal for one Hog, and their subtle Nature is wholly lost to them. Learn then, o my Son, this Mystery of Œconomy, and apply it faithfully and with Diligence in thy Work.
 On the Mystery of Œconomy [Knowledge, Wisdom]