Occult virtues and the soul of the world

The magnet attracts iron, yet no combination of hot, cold, dry and moist seems to explain why. Questions of this kind give rise to the theoretical heart of Agrippa's first book. Alongside the manifest qualities of the elements there exist, in his view, hidden virtues, which he calls occult because their causes remain invisible to the senses and to ordinary reason. They are known only through their effects, observed through experience and handed down by the ancient authors.

A problem of natural philosophy

The concept of an occult quality was not an invention of magicians. Medieval philosophers and physicians used it routinely to designate properties that acted through the whole form of a substance rather than through its elements: the attraction of the magnet, the action of poisons and the action attributed to antidotes. Agrippa takes up this scholastic notion and transforms it, making it the key to a vision of the cosmos in which each thing is tied to the others by invisible threads.

Agrippa lists many examples of such properties, taken from tradition: the torpedo fish that numbs the hand of whoever touches it, the remora, a small fish which according to Pliny could hold ships back, amber that draws straws to itself. For the sixteenth-century reader these were facts of the same kind, some observable, others inherited from books, and all demanded a cause that the elements could not supply.

From ideas to things

Where do these virtues come from? Agrippa answers with a chain of derivations of Platonic descent. The ideas exist in the divine mind as models of all things; the soul of the world, which animates the whole universe as the human soul animates the body, receives their forms; through the rays of the stars these forms descend onto earthly matter and imprint their qualities on it, provided that the matter is disposed to receive them.

The passage, however, requires an intermediary. Between the soul of the world, which is spiritual, and the body of the world, which is material, Agrippa places the spirit of the world, which he also calls the quintessence because it is not composed of the four elements. It is a most subtle substance, almost body and almost soul, spread everywhere. The idea comes largely from Ficino, who in De vita coelitus comparanda, the third of his Libri de vita of 1489, had described this spiritus as the vehicle of celestial influences.

The signs imprinted in things

If occult virtues come from the stars, can they be recognised? Agrippa thinks so. Things, he says, often bear the signs of the heavenly body on which they depend: shapes, colours, lines, behaviours. Some plants follow the Sun, some stones show markings that recall stars or figures, certain animals seem to imitate the rhythms of the Moon. This doctrine of signatures, already present in medieval authors, would enjoy great success in the sixteenth century, down to Paracelsus and beyond.

The resulting picture is that of a speaking nature, full of correspondences that the wise man learns to read like a book. For Agrippa natural magic does not violate the laws of the world but follows them, bringing kindred things together so that their virtues reinforce each other. It was a theory of causation, now superseded by modern science, which nevertheless helped generations of scholars to ask questions about the hidden order of nature. Many of his contemporaries, after all, saw no contradiction between observing nature and searching for its secret correspondences.