THESIS I.

Sleep contrary to nature, properly called Sopor (Subeth in Arabic), either occurs by itself or arises through sympathy; and both either exist without a fever or have a fever joined to them.

II.

That which afflicts with a fever is either a perpetual companion of the fever, or it is present only at times. The latter is a symptom of the fever, the former is not; although it is excited by almost the same cause.

III.

That which has a slow fever perpetually conjoined to it is called λήθαργος [lethargus]. It is distinguished from καταλήψει [catalepsy] or κατοχῇ [katochē], from καταφορᾷ [kataphorā] or coma, etc., in that these affections either subsist without a fever or hold only the status of a symptom.

IIII.

From these things it is evident that lethargy, insofar as it is a symptom (for it also denotes a disposition, the cause of this symptom), is a somnolent sluggishness, or a certain drowsiness with a slow, perpetual fever.

V.

The cause of this symptom is not from the number of παθῶν [pathōn] or simple accidents, but of those that are συνδεδυασμένων [syndeduasmenōn] (compounded).

VI.

However, such πάθη [pathē] are not defined properly (which belongs only to substance, as Aristotle witnesses in the 7th of the Metaphysics), but through the δεκτικὸν πρῶτον [dektikon prōton] (primary recipient) and the ὁμόγονον [homogonon] cause (called by physicians the συνεκτικὴν [synektikēn] or containing cause), because of which they inhere in a certain subject.

VII.

The subject of lethargy is the brain. For how will the external senses, as well as motions, cease contrary to nature, while that part which holds the status of the principle of sense and motion remains unharmed?

VIII.