The Philosophy of Natural Magic, by Henry Cornelius Agrippa, L. W. de Laurence ed. , at sacred-texts.com
There are, then, as we have said, four Elements, without the perfect knowledge whereof we can effect nothing in Magic. Now each of them is three-fold, that so the number of four may make up the number of twelve; and by passing by the number of seven into the number of ten, there may be a progress to the supreme Unity, upon which all virtue and wonderful operation depends. Of the first Order are the pure Elements, which are neither compounded nor changed, nor admit of mixtion, but are incorruptible, and not of which, but through which the virtues of all natural things are brought forth into act. No man is able to declare their virtues, because they can do all things upon all things. He which is ignorant of these, shall never be able to bring to pass any wonderful matter. Of the second Order are Elements that are compounded, changeable and inpure, yet such as may by art be reduced to their pure simplicity, whose virtue, when they are thus reduced to their simplicity, doth above all things perfect all occult and common operations of Nature; and these are the foundation of the whole Natural Magic. Of the third Order are those Elements, which originally and of themselves are not Elements, but are twice
compounded, various and changeable one into the other. * They are the infallible Mediums, and therefore are called the middle nature, or Soul of the middle nature. Very few there are that understand the deep mysteries thereof. In them is, by means of certain numbers, degrees and orders, the perfection of every effect in anything soever, whether Natural, Celestial or Supercelestial; they are full of wonders and mysteries, and are operative, as in Magic Natural, so in Divine: For from these, through them, proceed the bindings, loosings and transmutations of all things, the knowing and foretelling of all things to come, also the driving forth of evil and the gaining of good spirits. Let no man, therefore, without these three sorts of Elements, and the knowledge thereof, be confident that he is able to work any thing in the occult Sciences of Magic and Nature. But whosoever shall know how to reduce those of one Order into those of another, impure into pure, compounded into simple, and shall know how to understand distinctly the nature, virtue and power of them in number, degrees and order, without dividing the substance, he shall easily attain to the knowledge and perfect operation of all Natural things and Celestial secrets.
45:* Such as heat, light and electricity; astral magnetism, attraction and vibration; form, number and color; occult principles of natural law; the immutable attributes of time, space and substance.