This volume takes the place at least in time of two volumes published some years ago which contained verbatim stenographic reports of lectures delivered by the author during 1927. These earlier volumes entitled Theosophy and Modern Science had a very gratifying reception7Tiot only by Theosophists but others but the book having been for some time out of print, it was suggested the two volumes might be condensed into a single one by the process of eliminating all matter extraneous to the main theme and which was the mere consequence or product of the style intentionally used in the lectures themselves. It is obvious that lectures delivered from a public platform of necessity are different both in type and in content to some extent from literary works written for study and reference. I hesitated before accepting this excellent suggestion, as I had neither the time nor the intellectual leisure to undertake this work of revision myself, and had it not been for the very kindly offer of Miss Helen Savage, one of the sub-editors of The Theosophical Forum, it might have been years before the present volume could have been put into circulation. It is entirely due to her unremitting efforts and enthusiastic application, assisted by one or two helpers, that the present book appears today. I have myself carefully gone over the manuscript submitted to me by Miss Savage and take this occasion to express to her my grateful and genuine appreciation of the way in which this work of revision has been accomplished by her. It also gives me genuine pleasure to express my sincere gratitude to the staff of Theosophical University Press for the admirable and accurate work resulting in this present volume imbodies all the essential Theosophical teachings contained in the former Theosophy and Mod ern Science as well as a number of new footnotes dictated by myself, and certain other additions which it seemed to me would strengthen the argument or illustrate different points of teaching or of thought. No attempt has been made in the text, however, to adduce newer and later scientific arguments in favour of the Theosophical position because frankly I did not consider these necessary. It is not intended as a work brought up to date to conform with the latest biological or evolutionary or anthropological theories and discoveries, but is an attempt to set forth very definite and clear-cut Theosophical doctrines and the illustrations and scientific material which I used when delivering the lectures are as useful here as they were formerly because they merely were the scientific background upon which I then painted the Theosophical picture which I had in mind. It should be clear, then, that it is the Theosophical doctrine which is the important point and although it would be interesting and perhaps helpful to some types of minds to have the latest pronouncements of scientific research brought to bulwark the Theosophical position, this, as said above, was not considered necessary.