Boyle first argued that fire is not a universal and sufficient analyzer of dividing all bodies into their elements, contrary to
Jean Beguin and
Joseph Duchesne. To prove this he turned for support to
Jan Baptist van Helmont whose
Alkahest was reputed to be a universal analyzer. Boyle rejected the Aristotelian theory of the
four elements (earth, air, fire, and water) and also the three
principles (salt, sulfur, and mercury) proposed by
Paracelsus. After discussing the classical elements and chemical principles in the first five parts of the book, in the sixth part Boyle defines
chemical element in a manner that approaches more closely to the modern concept: :I now mean by Elements, as those Chymists that speak plainest do by their Principles, certain Primitive and Simple, or perfectly unmingled bodies; which not being made of any other bodies, or of one another, are the Ingredients of all those call'd perfectly mixt Bodies are immediately compounded, and into which they are ultimately resolved. However, Boyle denied that any known material substances correspond to such "perfectly unmingled bodies." In his view, all known materials were compounds, even such substances as
gold,
silver,
lead,
sulfur, and
carbon. ==Influence==