The book is founded mainly upon a study of the herbals themselves. My attention was first directed to these works by reading a copy of Lyte’s translation of Dodoens’ Herbal, which happened to come into my hands in 1894, and at once aroused my interest in the subject. I have also drawn freely upon the historical and critical literature dealing with the period under consideration, to which full references will be found in Appendix II. The materials for this work have chiefly been obtained in the Printed Books Department of the British Museum, but I have also made use of a number of other libraries. I owe many thanks to Prof. Seward, F.R.S., who suggested that I should undertake this book, and gave me special facilities for the study of the fine collection of old botanical works in the Botany School, Cambridge. In addition I must record my gratitude to the University Librarian, Mr F. J. H. Jenkinson, M.A., and Mr C. E. Sayle, M.A., of the Cambridge University Library, and also to Dr Stapf, Keeper of the Kew Herbarium and Library. By the kindness of Dr Norman Moore, Harveian Librarian to the Royal College of Physicians, I have had access to that splendid library, and my best thanks are due to him, and to the Assistant-Librarian, Mr Barlow. To the latter I am especially indebted for information on bibliographical points. I have also to thank Mr Knapman of the Pharmaceutical Society, Dr Molhuizen, Keeper of the Manuscripts, University Library, Leyden, and the Librarian of the Teyler Institute, Haarlem, for giving me opportunities for examining the books under their charge. The great majority of the illustrations are reproduced from photographs taken directly from the originals by Mr W. Tams of Cambridge, to whom I am greatly indebted for the skill and care with which he has overcome the difficulties incidental to photographing from old books, the pages of which are so often wrinkled, discoloured or worm-eaten. For the use of Plate XVIII, which appeared in _Leonardo da Vinci’s Note-Books_, I am under obligations to the author, Mr Edward M^{c}Curdy, M.A., and to Messrs Duckworth & Co. Text-figs. 7, 18, 77, 78 and 112 are reproduced by the courtesy of the Council of the Bibliographical Society, from papers by the late Dr Payne, to which the references will be found in Appendix II, while, for the use of Text-fig. 108, I am indebted to the Royal Numismatic Society. For permission to utilise the modern facsimile of the famous Dioscorides manuscript of Juliana Anicia, from which Plates I, II, and XV are derived, I have to thank Prof. Dr Josef Ritter von Karabacek, of the k. k. Hofbibliothek at Vienna. In connection with the portraits of herbalists here reproduced, I wish to acknowledge the generous assistance which I have received from Sir Sidney Colvin, formerly Keeper of Prints and Drawings, British Museum.