Dr. John Dee's history has often been written, and the catalogue of the MSS. he owned has long been in print in a Camden society volume (_Diary of Dr. John Dee_) edited by Halliwell. The main facts of his life that concern us are that he lived at Mortlake, and in 1584 went on a wild journey to Poland. In his absence his house and collections were plundered by a mob, who, not without excuse, thought him a warlock. When he returned in 1589 he set himself to recover his scattered property, and to a great extent succeeded. He moved from Mortlake to Manchester, being made Warden of the college there in 1595; later on he returned, and died at Mortlake, much in debt, I think, in 1608. I find from Archbishop Ussher's printed correspondence that his books were still unsold in 1624; litigation may have prevented their being dealt with earlier. The lists we have of his MSS. date from before his foreign tour; that which is in print was made on the eve of his departure, and contains a little over 200 entries. After the vicissitudes which his collection suffered it is remarkable that one should still be able to identify as extant well over half of it. I have been helped in my searches by certain marks--a little ladder, or the astrological sign of Jupiter, or a [Greek: Delta]--which occur on the first page of many. His handwriting, too, in notes, and certain names of owners (particularly P. Saunders) are guides. Some of his MSS. were bought by Ussher, and are at Trinity College, Dublin, and a few were bought by Cotton. But the largest group of them is at Corpus Christi College, Oxford. These were acquired by the great Oxford antiquary, Brian Twyne, who hoped that his college would buy them from him, but this they would not do. Happily Twyne was not too much hurt by the refusal to leave them to the college at his death. I guess that one reason for his buying them was that some (perhaps many) of them had once belonged to his grandfather, John Twyne, a Canterbury man of some slight eminence, who in his turn had secured a considerable "lot" of MSS. from the library of St. Augustine's Abbey. In searching out the relics of that great library I found the combination, or pedigree, St. Augustine's--John Twyne--Dee--Brian Twyne--Corpus Christi, to be a frequent one, and this set me upon a general investigation of Dee's MSS. A little notebook of his at Corpus Christi showed that in early life he had borrowed a number of MSS. from Peterhouse and from Queen's College, Oxford. I did not find that these ever got back to their sources, but I do not think that Dee was dishonest in the matter; I believe he was allowed to keep them for some consideration received. Some of the Peterhouse books are traceable in the Ashmole collection, the Pepys Library, and the British Museum; of those of Queen's College I can say nothing. Dee was specially interested in mathematics, alchemy, and, as everyone knows, converse with spirits, but his library was not confined