12. The College took pride in resuming at once its position in the world of letters and science, and the following years are famous for the work of Pearson and Barrow, two great divines of the time, and above all of Isaac Newton. The influence of the last-named philosopher on the studies and intellectual life of Cambridge was far reaching. His discoveries in pure mathematics, mechanics, physics, and dynamical astronomy were of the utmost importance, and made Cambridge the centre of mathematical work in England. I will show you to-morrow the rooms he occupied and in which he wrote his famous _Principia_. The staircase on which these rooms are situated has had other distinguished occupants: the rooms on the ground floor on the right-hand side on entering it were occupied by Thackeray, and subsequently by the late astronomer-royal; those on the opposite side by Macaulay; the rooms on the first floor next the gate which once had been occupied by Isaac Newton, were used later by Lightfoot, the theologian, and Jebb, the Greek scholar; and those on the opposite side by Sir James Frazer, who has done so much to investigate the beliefs of primitive man. This is an interesting group of men, but in fact there are few rooms in College which have not been inhabited at some time by those who have made their names famous. 13. Barrow held the mastership from 1673 to 1677. On his initiative the College erected, on the west side of Nevile's Court, the magnificent library which is now stored with literary treasures. This is another building to which we must pay attention to-morrow, and with it we may associate the adjoining chambers. From the close of the seventeenth century onwards we can describe life in College, especially among undergraduates, in considerable detail. The usual age of entry had risen to seventeen or eighteen. To the dons the College offered a comfortable home until an opportunity occurred of taking a college living, and it must be admitted that some were beginning to be content to consider it as nothing more. Materials for the history of the time and the following century have been published by Christopher Wordsworth.