[Below, Castiglioni comments on Agrippa's ideas about "natural magic," commending his attempt, "with a magnificent intuition of the truth, to lead magic into the highroad of the observation of nature."]

Throughout Europe, and particularly in Italy of the fifteenth century, with the revival of learning a first attempt is made by some great scholars to inquire into the problems of the universe, by trying to explain its mysteries rationally. The Humanist, home doctus, becomes the type of the new epoch, taking the place of the homo sanctus….

The idea of the magic action of the word, of the perfection of alphabetical characters, of the value of symbol, which … was fundamental to the magic of the ancients, springs up again in a new form, higher, vaster, and more complete. The value of letters, words, and symbols was derived from the shared secret, the intellectual communion, of those understanding it. Upon the basis of this idea an entire system was slowly built up at the time when culture began to spread and the return to the classic spirit became visible in Humanism, and the revival of Greek philosophy became manifest. The significance of symbol and letter, like that of the opus magnum of alchemists and the calculations of astrologers, is, above all, philosophical and strives for a natural explanation. Ancient magic changes with the change of ideas, with the succession of new spiritual and social events modifying the milieu: the observation of nature, which begins to attract the attention of scholars as the fundamental element of research, attains predominance. Agrippa of Nettesheim, Theophrastus Paracelsus, and G. B. della Porta are the founders or, rather, the organizers of these ideas in a system of natural magic. Restless and independent spirits overwhelmed by struggle and conflict in times of bitter religious and civil wars, thinkers both rebellious and still mystical, impassioned observers still fettered by the bonds of ancient magic beliefs, they are the towering and characteristic figures of that transitional epoch in which natural magic appears and is universally accepted.

Natural magic marks a further stage in the evolution of primitive magic towards experimental science. It detaches itself from the fundamental magic concept as well as from the religious idea, borrows its form of reasoning from philosophy, but adheres to reality in so far as its observations are concerned. Natural magic slowly develops from primitive magic, as observation proceeds and method advances according to the speed with which critical faculties subdue the emotional ones, and the human mind forsakes the notion of supernatural beings and their intervention and seeks for the explanation of nature in the forces of nature itself. Natural magic, on its way to becoming science, carries with it, for a long time, a large part of its ancestral heritage of primitive magic and with difficulty frees itself from some of its beliefs, especially from those most firmly anchored in the deepest strata of the mind…. [The] earliest writers, champions of the magic idea and disseminators of occult sciences, repeatedly glimpsed the necessity of criticism and of experience. In an earlier epoch only a few single, isolated individuals faced this problem. Later more and more scholars and research workers, though assuming different attitudes in regard to magical and mystical problems, created a new current of ideas. Maxwell rightly remarks [in La Magie, 1925] that this new orientation was earlier manifest in the domain of physical and natural problems, as they lend themselves more readily to observation and criticism.

The evolution of the psychic phenomena of witchcraft is more laborious because the problems are more complex, the causes less easy to establish, and the results less controllable. All the problems concerning the mind remain much longer under the rule of magic and mysticism, because many of them do not appear sufficiently clear. Not until our day has scientific research on the functioning of the brain and on the unconscious, determining the characteristics and origins of certain psychic states (such as hypnotism, suggestion, double personalities, dreams), raised the veil of mystery and illuminated a series of formerly occult phenomena by the light of observation and criticism.

Natural magic begins with the study of atmospheric and astral phenomena and establishes a link between the individual and the elements. It asserts that all phenomena are sympathetically co-ordinated. This doctrine of sympathy enables the practitioners of natural magic to imagine the existence of secret relations and incantational connections. The inborn secret link is asserted between things and their names, which contain the power of the things in the form of their expression. The magic strength of the word derives from its relationship with the thing it designates, and the magical properties of things originate in their forms.

Agrippa of Nettesheim (1456-1535) is the first of the great figures ushering in the new era. The history of his life is a perfect illustration of his studies and mentality. Born of an ancient noble family, he assiduously devoted himself from an early age to the study of languages and passionately collected all the literature on occult sciences, tried his hand at alchemy, and at twenty founded a society for the study of secret sciences in Paris. He lived in France, and visited England and Germany, indefatigably preaching his ideas. He was often persecuted by the ecclesiastical authorities. He wrote his De occulta philosophia, which made him famous, in 1510, fought with the Imperial troops against the Venetians, and was knighted on the field of battle. Later he was obliged to defend himself against the accusations of the inquisitors. At Metz, where he supported the cause of some persons who were accused of witchcraft and succeeded in saving them from the death penalty, he himself was accused of being an accomplice of the accused and was forced to flee to Lyon, where he was appointed physician to the King of France. He later became historian at the court of Margaret of Austria, and a physician in Cologne. At last he returned to Lyon, was persecuted by his enemies and misfortune, and died in 1535, famed as a sorcerer.

Among new ideas in the process of formation, and amid the conflict between ancient magic conceptions and the new way of thinking, Agrippa attempted, with a magnificent intuition of the truth, to lead magic onto the highroad of the observation of nature and to explain diabolic and supernatural phenomena as the results of natural forces. Magic occurrences appeared to him as demonstrations and applications of scientific truths; the doctrine of the "sympathy and antipathy of things," which was a fundamental part of ancient Italic philosophy, was reborn. With the decline of Galen's anatomy, of Aristotle's physics, of Ptolemy's astronomical system, ancient magic was gradually forsaken by its followers. Agrippa of Nettesheim, who was called the last of the sorcerers, but might be called the first of the naturalists, placed the idea of magic on a new basis and perceived that everything formerly attributed to magic must be assigned to nature instead.

Natural magic, according to Agrippa, is a science. He claims that a direct and reciprocal relationship exists between the highest and the lowest things, and asserts that every thing is attracted by its likes, which in turn it attracts with all its forces. These secret forces are a part of the spiritual world where ideas exist. However, according to Agrippa, ideas cannot act over things by themselves, nor can matter be put in motion by itself. A medium is necessary, a vital force that can transfer the activity of the spirit to the body, and this medium is the quintessence, the fifth essence, since it is not composed of the four elements but exists beyond and above them. It fulfils the same function in the world as the soul does in the human body, and is therefore the soul of the world. It irradiates from the planets, and the occult qualities of living substances such as minerals and metals stem from it. It may be extracted from one substance and transferred to another. Because of it fire rises towards celestial fire and water flows towards the waters; living beings convert their nourishment into the substance of their organism; and stars, precious stones, plants, and animals exert an influence over men. Its signs are marked on the earth, plants, and man's organs (law of the signatures).

Natural magic, according to Agrippa, must, therefore, no longer admit the performance of magic and forbidden operations with the help of the supernatural, but has to search for the secret laws of nature and the utilization of natural forces. Sorcerers, according to this conception, become the priests of science.

In such a scientific belief the magic power of words, however, is important. This doctrine, which goes back to Neoplatonic philosophy but whose beginnings may be traced to a much remoter era, claims that words and names are but the reflection of the creative power of "forms" in God's mind. The same is true of writings. A speech composed of many words has a power greater than that possessed by an isolated word. The value of a magical spell depends on enunciation, on the rhythm and the enthusiasm with which it is uttered, on the emotion and conviction of the sorcerer. Agrippa mentions the example of Orpheus, and states that incantations, uttered with vehemence and passion and under careful observation of the measure and number of their words, endow the enchanter with tremendous strength due to the impetuous outburst of his imagination, and are projected on the object of the spell, binding and directing it in accordance with the desires and words of the magician. The true instrument of spellbinding is a sort of breath, pure, harmonious, and alive, which embodies movement and will, is skilfully composed, endowed will deep feeling, and conceived by reason.

Maxwell rightly observes that Agrippa thereby voices a perfectly modern psychological idea: the idea that the strength of the spell is dependent on the emotional intensity of the spell-caster, and that magical strength dwells in the sphere of passions, whereas reason must conceive the purpose and prepare the methods to encompass it. According to Agrippa, reason's task is to calculate the position of the stars or the numerical proportions between words and things or the mutual relations of things; the task of emotion is that of imparting its direction and force to the magical action. Thus natural magic and modern psychology are closely linked in the evaluation of the power of suggestion.