hail, dew and the like, as well as the Moon’s halo and earthquakes. In general, Theophras-
tos attempts to correlate varieties of phenomena with their different causes. In On Winds,
Theophrastos discovers multiple causes of winds and adopts no one as the primary cause.
While he generally defines wind simply as movement of air (considered inadequate by
Aristotle, Mete. 1.13 [349a17–32]), he asks whether winds move in order to restore equi-
librium in the air. This imbalance is, in part, deductively attributed to the Sun and its
heat. The notion of the restoration of air’s equilibrium brings up the question of whether
Theophrastos admitted the idea of horror vacui. On (Weather) Signs, attributed to Aristotle in
manuscripts but to Theophrastos in modern editions, has been conclusively shown not to
have been authored by either: cf. -T.
Of the three extant physiological works, On Fatigue begins with a discussion of seats of
fatigue in the blood vessels, tendons, joints, and even bones. He moves to their causes, symp-
toms, and therapies. Individual cases of fatiguing exertions follow, after which Theophrastos
returns to therapies, concluding with remarks on constitutional dispositions toward fatigue.
He presents no classification of different types of fatigue; the treatise appears disorderly. He
does, however, present his favored explanation of the general cause of fatigue: col-
liquescence (sunte ̄xis), the product of liquefaction of bodily wastes arising due to the motion
of bodily parts in exercise or exertion. These fluids are not excreted like other natural bodily
wastes (peritto ̄mata) but permeate the body and settle in various places, e.g., joints, especially
sinewy ones. One symptom upon which he dwells is the feeling of being weighed down by
the sunte ̄xis, essentially a hydraulic explanation leading to a hydraulic therapy – remove
excess fluid and fatigue disappears. In On Sweat, rather than answer fundamental questions
about the occurrence of sweating, Theophrastos turns his attention to certain qualities of
sweat, e.g., saltiness and bad odor. He concludes that saltiness is due to the secretion of
unconcocted matter not natural in the body; foul odor is due to imperfect concoction due to
bodily condition, age, and eating certain foods. The sweat of young people, he says, smells
worse than older people’s due to their sexual drive, open pores, and continued bodily
change, i.e., their bodies are less stable. A brief excursus on eruptions or ulcers of the skin
due to sweating explains that skin sores may result if exercise fails to remove impurities
along with sweat,. Various briefly-considered problems associated with sweating follow but
are not conclusively answered. On Dizziness deals with a sensation involving disequilibrium
and lack of coordination between vision and bodily position occurring from rotational
movement, looking at moving objects, looking down from elevations. This dizziness can
be accompanied by blurred vision and, in extreme instances, unconsciousness. Although
Theophrastos recognizes multiple causes for dizziness, he still attempts to settle on one
explanation – separation or imbalance of fluid in the head caused by some interference with
that fluid’s natural condition. Pho ̄tios preserves excerpts from two other physiological works.
In On Paralysis, Theophrastos explains that interruption of the flow of breath (pneuma) by
pressure causes paralysis. The breath becomes trapped, triggering cooling and loss of heat
in the afflicted area. In On Fainting, he considers fainting due more to the effects of hot and
cold than breath. It happens from loss of heat occurring for various reasons: sudden cooling
of the body can occur with excessive blood loss or when external heat overpowers the
body’s inner heat.
There is no clear evidence that Theophrastos seriously criticized Aristotle’s scientific
methods of inquiry, but rather basically accepted his mentor’s hierarchical division of
nature. He often develops, refines, and improves ideas already present in Aristotle’s writings:
resolving loose ends, continuing discussions initiated by Aristotle, or clarifying ideas which
THEOPHRASTOS OF ERESOS