tentive to administer every help of art, when the disorder shews itself.

I, on the contrary, say, prepare not at all; think of no outlets; and when the disorder comes, trust to nature.

These propositions I purposely premise, that the reader, startled at their seeming absurdity, may the more attentively examine what I have to offer to support them.

Though I should be right, I hardly expert that all operators will, at least for a long while come into my way of thinking. But I entertain better hopes from those physicians, whom knowledge and virtue place above prejudice, trust to time, which sooner or later silences passion, and gets the better of prepossession; and should I be disappointed, I flatter myself to find a sufficient reward in the testimony of my conscience, that I have always fought the good of mankind, and laboured for the discovery of truth.

The doctrine which I endeavour to demonstrate is so plain, that I might have brought it within the compass of a few pages; but it is necessary to explain it, and to establish it upon proofs, in order to remove the prejudices still entertained by many people.

All I have to say will be reduced to three heads. The first regards the preparation; the second, the insertion; the last, the treatment of the disorder. I intend, as much as possible, to forbear any enquiry which does not directly tend to my object, viz. the best method of inoculating.