Those hypotheses do not a little hinder the progress of Humane knowledge, that introduce Morals and Politicks into the Explications of Corporeal Natu… - Robert Boyle

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

Among Latin writers, the acceptations of the word nature are so many, that I remember, one author reckons up no less than fourteen or fifteen. Hence we see how easy 'tis for the generality of men, without excepting those who write of natural things, to impose upon others and themselves, in the use of a word so apt to be mis-employ'd. ..the very great ambiguity of this term, and the promiscuous use made of it, without sufficiently attending to its different significations, render many of the expressions wherein 'tis employ'd either unintelligible, improper, or false.

As for silver, I never could see any degree of fire make it part with any of its three principles. ...But admitting, that some parts of the silver were driven away by the violence of the fire, what proof is there, that it was either the salt, the sulphur, or the mercury of the metal, and not rather a part of it homogeneous to what remained? for besides that the silver, that was left, seemed not sensibly altered, which probably would have appeared, had so much of any one of its principles been separated from it.