Principle, element and metal

The principles work alongside the four elements and the seven planet-metals in alchemy's layered theory of matter: the elements as the basic qualities, the principles (sulphur, mercury, salt) as the active natures, and the metals as the substances they compose. Paracelsus's tria prima in particular reshaped alchemy and early chemistry and medicine.

The atlas gives each principle its nature and its role in the theory. The metals and elements the principles relate to are treated in their own categories, and the alchemical operations under Texts & the Canon.