In 1912 it was acquired by Wilfrid M. Voynich, hence its name. This letter was found inside.
Transcript and translation follow, courtesy of Philip Neal. Image courtesy of the Beinecke Library.
Image: Beinecke Library
Reuerende et Eximie Domine in Christo Pater
Librum hunc ab amico singulari mihi testamento relictum, mox eundem tibi amicissime Athanisi ubi primum possidere coepi, animo destinaui: siquidem persuasum habui a nullo nisi abs te legi posse. Petijt aliquando per litteras ejusdem libri tum possessor judicium tuum parte aliqua a se descripta et tibi transmissa, ex qua reliqua a te legi posse persuasum habuit; uerum librum ipsum transmittere tum recusabat in quo discifrando posuit indefessum laborem, uti manifestum ex conatibus ejusdem hic una tibi transmissis neque prius huius spei quam uitae suae finem fecit. Verum labor hic frustraneus fuit, siquidem non nisi suo Kirchero obediunt eiusmodi sphinges. Accipe ergo modo quod pridem tibi debebatur hoc qualecunque mei erga te affectus indicium; huiusque seras, si quae sunt, consueta tibi felicitate perrumpe. retulit mihi D. Doctor Raphael Ferdinandi tertij Regis tum Boemiae in lingua boemica instructor dictum librum fuisse Rudolphi Imperatoris, pro quo ipse latori qui librum attulisset 600 ducatos praesentarit, authorem uero ipsum putabat esse Rogerium Bacconem Anglum. ego judicium meum hic suspendo. tu uero quid nobis hic sentiendum defini, cujus fauori et gratiae me totum commendo maneoque.
Pragae 19. Augusti
Joannes Marcus Marci
Reverend and Distinguished Sir; Father in Christ:
This book, bequeathed to me by an intimate friend, I destined for you, my very dear Athanasius, as soon as it came into my possesion, for I was convinced it could be read by no-one except yourself.
The former owner of this book once asked your opinion by letter, copying and sending you a portion of the book from which he believed you would be able to read the remainder, but he at that time refused to send the book itself. To its deciphering he devoted unflagging toil, as is apparent from attempts of his which I send you herewith, and he relinquished hope only with his life. But his toil was in vain, for such Sphinxes as these obey no-one but their master, Kircher. Accept now this token, such as it is, and long overdue though it be, of my affection for you, and burst through its bars, if there are any, with your wonted success.
Dr. Raphael, tutor in the Bohemian language to Ferdinand III, then King of Bohemia, told me the said book had belonged to the Emperor Rudolph and that he presented the bearer who brought him the book 600 ducats. He believed the author was Roger Bacon, the Englishman. On this point I suspend judgment; it is your place to define for us what view we should take thereon, to whose favor and kindness I ureservedly commit myself and remain,
At the command of your Reverence,
Prague 19 August 1665
Joannes Marcus Marci