He was... the first to define the relation of an element to a compound — Robert Boyle

"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."

"The phaenomena afforded by trades, are a part of the history of nature, and therefore may both challenge the naturalists curiosity and add to his knowledge, Nor will it suffice to justify learned men in the neglect and contempt of this part of natural history, that the men, from whom it must be learned, are illiterate mechanicks... is indeed childish, and too unworthy of a philosopher, to be worthy of an honest answer."

"And truly... if men could be persuaded to mind more the advancement of natural philosophy than that of their own reputations, it were not, methinks, very uneasy to make them sensible, that one of the considerablest services, that they could do mankind, were to set themselves diligently and industriously to make experiments and collect observations, without being over-forward to establish principles and axioms, believing it uneasy to erect such theories, as are capable to explicate all the phænomena of nature, before they have been able to take notice of the tenth part of those phænomena, that are to be explicated."

"For it has been truly observed by a great philosopher, that truth does more easily emerge out of error than confusion."

"A Person any Thing vers’d in the Writings of Chymists cannot but Discern by their obscure, Ambiguous, and almost Ænigmatical Way of expressing what they pretend to Teach, that they have no Mind, to be understood at all, but by the Sons of Art (as they call them) nor to be Understood even by these without Difficulty And Hazardous Tryalls."

"I shall take leave to think the worse, rather of the practice of the men than of the book of God."