I consider, that as generally as Chymists are wont to appeal to Experience, and as confidently as they use to instance the several substances separat… - Robert Boyle

And that you may know... what kind of writings I mean, I shall name to you the learned Gassendus his little Syntagma of Epicurus's philosophy, and that most ingenious gentleman Monsieur Descartes his principles of philosophy. For though I purposely refrained, though not altogether from transiently consulting about a few particulars, yet from seriously and orderly reading over those excellent (though disagreeing) books, or so much as Sir Francis Bacon's Novum Organum, that I might not be prepossessed with any theory or principles, till I had spent some time in trying what things themselves would incline me to think; yet beginning now to allow myself to read those excellent books, I find by the little I have read in them already, that if I had read them before I began to write, I might have enriched the ensuing essays with divers truths, which they now want, and have explicated divers things much better than I fear I have done.

I find that even Eminent Writers (such as Raymund Lully, Paracelsus, and others) do so abuse the termes they employ, that as they will now and then give divers things one name, so they will oftentimes give one thing, many Names; and some of them (perhaps) such, as do much more properly signifie some Distinct Body of another kind; nay even in Technical Words or Termes of Art, they refrain not from this Confounding Liberty; but will, as I have Observ'd call the same Substance, sometimes the Sulphur, and Sometimes the Mercury, of a Body.

Epicurus... supposes not only all mixt bodies, but all others to be produced by the various and casual occursions of atoms, moving themselves to and fro by an internal principle in the immense or rather infinite vacuum.