h
century.

{207}

A curiously interesting episode that deserves a place in the history
of Papal Physicians occurred during Alderotti's life. One of the Popes
elected to fill the Papal chair had been earlier in life a physician.
This was the famous Peter of Spain, though he was really a Portuguese,
who, under the name of John XXI., occupied the Papal throne during the
years 1276-1277. Peter of Spain had been one of the most distinguished
natural scientists of this interesting century. Dr. J. B. Petella, in
an article published in Janus about ten years ago, entitled A Critical
and Historical Study of the Knowledge of Ophthalmology of a
Philosopher Physician who became Pope, gives an excellent account of
the life of Pope John XXI. [Footnote 27]

[Footnote 27: Janus, Archives International es pour l'histoire de la
Medicine et pour la Geographie Medicale, paraissant tous les deux
mois. Amsterdam, 1897-1898.]

Petella does not hesitate to say of him that he was "one of the most
renowned personages of Europe during the thirteenth century, from the
point of view of the triple evolution of his extraordinary mind, which
caused him to make his mark in the physical sciences, in the
metaphysical sciences, and in the religious world. In him there was an
incarnation of the savant of the time, and he must be considered the
most perfect encyclopedist of the Middle Ages in their first
renascence."

Anyone who reads Dr. Petella's account of this book by Pope John XXI.
will be surprised at how much was known about diseases of the eye at
the middle of the thirteenth century. For instance, hardening of the
eye is spoken of as a very serious affection, so that there seems to
be no doubt that the condition now known as glaucoma was recognized
and its bad prognosis appreciated. His account of the external anatomy
of the eye, eight coats of which he describes, beginning with the
{208} conjunctiva and ending with the retina, is quite complete. The
eye is said to have eight muscles, the levator of the upper eyelid and
the sphincter muscle of the eye being counted among them. The other
muscles are picturesquely described as reins, that is, guiding ribbons
for the eye. Cataract is described as water descending into the eye,
and two forms of it are distinguished--one traumatic, due to external
causes, and the other due to internal causes. Lachrimal fistula is
described and its causes discussed. Various forms of blepharitis are
touched upon.