To give the Reader an account, Why the following Treatise is suffer’d to pass abroad so maim’d and imperfect, I must inform him that ’tis now long since, that to gratify an ingenious Gentleman, I set down some of the Reasons that kept me from fully acquiescing either in the Peripatetical, or in the Chymical Doctrine, of the Material Principles of mixt Bodies. This Discourse some years after falling into the hands of some Learned men, had the good luck to be so favourably receiv’d, and advantageously spoken of by them, that having had more then ordinary Invitations given me to make it publick, I thought fit.
