chapters to the causes, symptoms, diagnosis and treatment of headache,
hemicrania, epilepsy, catalepsy, analepsy, cerebral congestion,
apoplexy and paralysis, phrenitis, mania and melancholia, incubus
or nightmare, lethargy and stupor, lippothomia or syncope, sciatica,
spasm, tremor, tetanus, vertigo, wakefulness, and jectigation
(jactitation, formication, twitching).

The third book of the Compendium opens with several chapters on
the anatomy and physiology of the eye and the phenomena of vision.
According to Gilbert, the eye consists of three humors, the
albugineous (aqueous), the crystalline lens and the vitreous humor,
and seven tunics, apparently

1. The conjunctiva
2. The albuginea or sclerotic
3. The cornea
4. The secundina (choroid)
5. The rethilea (retina)
6. The aranea (iris)
7. The uvea perforata (posterior layer of iris),

though the definitions are not in all cases quite clear and definite.
The tela aranea is said to take its origin from the retina, the retina
from the optic nerve, and the latter from the rethi (rete, network)
involving the substance of the brain. The cornea arises from the
sclerotic tunic, the uvea and secundina take their origin from the
pia mater, and the conjunctiva from a thin pellicle or membrane which
covers the exterior of the cranium and is nourished by a transudation
of the blood through the coronal suture. This pellicle is also said
to have a connection with the heart, which arrangement furnishes a