 He, therefore, bought an English edition of Euclid's "Elements" which included an index of propositions, and, having turned to two or three which he thought might be helpful, found them so obvious that he dismissed it "as a trifling book", and applied himself to the study of René Descartes' "Geometry".It is reported that in his examination for a scholarship at Trinity, to which he was elected on 28 April 1664, he was examined in Euclid by Dr Isaac Barrow, who was disappointed in Newton's lack of knowledge of the subject.Newton was convinced to read the "Elements" again with care, and formed a more favourable opinion of Euclid's merit.