Sydenham, Locke and Sydenham's De peste sive febre pestilentiali.

The second edition of Sydenham's Methodus curandifebres (1668) had an added chapter on plague and its treatment which he reprinted virtually unchanged in his later book, Observationes medicae (1676, and subsequent editions). This chapter has an interesting paragraph which is unique in Sydenham's work: it mentions the opinions of other writers. Its origin appears to lie in Sydenham's association with John Locke at the time the paragraph was written. The paragraph in question comes on pp. 191-4 of the Methodus where Sydenham discusses the place of venesection in the treatment of plague.' He begins by disagreeing with Diemerbroeck's opinion that bleeding is harmful and then goes on to support his conclusion by giving the names of thirteen authors: "Ludovicus Mercatus, Joannes Costaeus. Nicolaus Massa, Ludovicus Septalius, Trincavellius, Forestus, Mercurialis, Altomarus, Paschalius, Andernachus, Pereda, Zacutus Lusitanus, Fonseca, aliique." He ends the paragraph with a long quotation from Leonardus Botallus, testifying to the value of bleeding. Diemerbroeck' s text refers to numerous other authors and often gives references to their books. What stands out is that the thirteen authors listed by Sydenham are also listed one after another as a group by Diemerbroeck, though not in the same order, plus "lanus Antonius Saracenus" and "Paulus Mongius" who may be Sydenham's "others" (aliique). Moreover, Sydenham uses the same forms for the names: e.g. "Nicolaus Massa" rather than "Massa"; and "Forestus" rather than "Petrus Forestus". It seems therefore that Diemerbroeck's book was the source of Sydenham's references. Sydenham himself is not likely to have owned the book. He is not known to have possessed a library and, indeed, he gives the impression of not being over-much concerned with anyone's experience but his own. The exact opposite was true of Locke, who was certainly acquainted with Sydenham by this time because he contributed a poem to the second edition of the Methodus. Throughout his life Locke kept a series of commonplace books crammed with notes on medicine, theology and other subjects that interested him. In one of them dated "25 Feb 1659" on the front endpaper, the latest books noted are Willis' Cerebri anatome, 1664 (see p. 8 1) and Timaeus' Epistolae et consilia, 1665 (see p. 45).2 On