ABSTRACT
This chapter provides a brief survey of some of the ways in which English mechanical philosophers tried to overcome or rather circumvent the perceived philosophical objections to a strict version of the mechanical philosophy by introducing unexplained active principles. It claims that the use of active principles in pre-Newtonian matter theory represents a clear and undeniable tradition in English mechanical philosophy and cannot be dismissed as nothing more than a series of minor aberrations by the writers involved. The chapter suggests why active principles played such a prominent part in seventeenth century English natural philosophy. It argues that the possible existence of occult active principles in matter was an important aspect of the promotion of the experimental method. The occult qualities or principles of matter, so important for understanding the true nature of God's creation, could only be evinced, it was claimed, by experimental procedures.
