The Geometriae Pars Universalis, published in Padua in 1668, presents a survey of the material Gregory studied while on his Continental trip. It summarizes the techniques of calculus prior to the discoveries of Newton and Leibniz.
Let the reader who has compared this work with others judge what is mine and what belongs to another.
The book contains the first published proof of the fundamental theorem of the calculus. It may not be an exaggeration to call this the first calculus text.