Amongst the manuscripts of the heirloom _Parentalia_ is a chronological _Series Vitæ et Actorum Domini Christophori Wren_ in four pages. This is a copy, perhaps even may be the draft, of the list in the Lansdowne Manuscript at the British Museum, which was initialed by Sir Christopher himself about a year before he died. I am bound to say, however, that even a list so apparently authentic gives me no confidence. Wren was the last man to be interested in materials for his own biography, and he was ninety when he checked the list. His son was incurably casual and inaccurate, and the Elmes, Phillimore, and Milman _Lives_ were based on it blindly, except in the case of Miss Milman, who used her own judgment somewhat. Elmes was laborious, and had access to a lot of material such as State Papers, some of which mysteriously got into his own possession; but he was almost blind, and he dated his dedication to Sir Humphry Davy exactly a hundred years before I date this, at a period when biography was no exact science. The time has come for someone to go back to all the originals, including many which have come to light since his day. I hope this work will not linger until February 25, 2023. For light on Wren as a scientist I make very grateful acknowledgments to my friend Sir Daniel Hall, K.C.B., F.R.S., an expert in the outlook of the philosophers of Wren’s day. He will recognise as his own a shamelessly large number of sentences in Chapter IV. Professor Hinks, F.R.S., the present Gresham Professor of Astronomy, has helped me with notes on that aspect of his great predecessor’s activities. Mr. Wells, the reigning Warden of Wadham, has kindly checked my chapter on Wren’s Oxford days. There is a common phrase for men of encyclopædic knowledge, that they have forgotten more than other men ever knew. It would be true of my old friend, Mr. Arthur Bolton, Curator of Sir John Soane’s Museum, but--he has not forgotten. He has been so helpful and full of suggestions that it would be more honest if his name were with mine on the title-page. But he shares Wren’s gift of modesty as well as learning, and I need only express an admiring gratitude. I am indebted to the Duke of Portland, to the Warden of Wadham, and to the Editor of _Architecture_ for permission to reproduce portraits. I have attempted no bibliography, in which Longman’s _Three Cathedrals_ would have a prominent place. That task and a schedule of Wren’s drawings, with reproductions of those that can be definitely attributed to him, will be amongst the fitting works of the projected Wren Society. CONTENTS CHAPTER PAGE PREFACE v AUTHORITIES AND ACKNOWLEDGMENTS vii I. PARENTAGE AND CHILDHOOD 1 II. OXFORD CAREER AND EARLY INVENTIONS 9