De Relatione Illusionum
Of this will I speak further with thee, for here behold a great Rock of Ignorance on the one Hand, and on the other a Whirlpool of Error; in this Strait are many Wrecks of Magick Ships. Knowest thou not that Riddle of old, whether it be lawful to pay Tribute to Caesar or no? Give therefore to the Body the Things of the Body, and to the Mind the Things of the Mind. Yet because of the interior Harmony of all Things that proceedeth from their Original One Nature, there is Action and Reaction of the one upon the other, as I have already set forth in this mine Epistle. But Law is universal, and between these two Kinds of Illusion there is an ordered Proportion, and it is proper to thy Science to delimit and describe this Law of Interaction, for to deny it wholly (as to extend it to Infinity) is Folly, born of Ignorance, Idleness, and Incapacity to observe Fact.
 On the Relations of Illusions