And first the Doctrine that all their Theory is grounded on, seems to me Inevident and undemonstrated, not to say precarious. - Robert Boyle

And of universal nature, the notion I would offer, should be something like this. Nature is the aggregate of the bodies, that make up the world, in its present state, considered as a principle, by virtue whereof, they act and suffer, according to the laws of motion, prescribed by the author of things.

I must confess (sayes Eleutherius) I have, in the reading of Paracelsus and other Chymical Authors, been troubled to find, that such hard Words and Equivocal Expressions, as You justly complain of, do even when they treat of Principles, seem to be studiously affected by those Writers; whether to make themselves to be admir'd by their Readers, and their Art appear more Venerable and Mysterious, or, (as they would have us think) to conceal from them a Knowledge themselves judge inestimable.

Those hypotheses do not a little hinder the progress of Humane knowledge, that introduce Morals and Politicks into the Explications of Corporeal Nature, where all things are indeed transacted according to Laws Mechanical.