Five-minute digest
Meteorology
Summary
Aristotle's Meteorology, in four books, studies 'things on high' (meteora) and much else besides: everything that happens in the region between the moon's sphere and the earth, together with the sea, rivers, earthquakes and, in Book IV, the way heat and cold work on matter. It begins by placing itself in a sequence. The Physics has treated motion and causes, On the Heavens the stars, On Generation and Corruption the elements and their changes; the Meteorology takes up events that are natural but 'less perfect' in order than the heavens, and it looks ahead to the books on animals and plants. The explanatory key of Books I to III is a theory of two exhalations rising from the earth under the sun's heat: a moist one, vapour, and a dry, smoky one. Vapour rising and cooling makes cloud, rain, dew, hoar frost, snow and hail. The dry exhalation, carried to the upper region and set alight by the heavens' motion, produces shooting stars and comets; Aristotle explains the Milky Way the same way. Moving horizontally it is wind; trapped inside the earth it causes earthquakes; forced out of cloud it makes thunder and lightning. Rivers, he argues, are not fed by one underground reservoir, as the myth in Plato's Phaedo claims, but by mountains that hold water like a saturated sponge. The sea's saltness comes from an earthy admixture, as urine and sweat carry the salty residue of undigested food, and he reports that evaporated salt water condenses fresh: 'This I know by experiment.' Book I closes with one of the work's most memorable arguments. Land and sea change places over immense spans of time, as rivers silt up and dry; Egypt, he argues, was built up by the Nile, and the shallowing of Lake Maeotis is measurable within sixty years. These changes follow cycles and do not mean the world is coming to be or passing away. Book III turns to optics, explaining halos, rainbows, mock suns and 'rods' as reflections of sight, and notes that the moon rainbow is so rare that he has seen only two in more than fifty years. Book IV, whose place in the work is debated, is an early chemistry: the hot and cold are active, the dry and moist passive, and processes such as ripening, boiling and putrefaction are defined by how a thing's own heat masters its moisture. Much of the physics is wrong, and the work's value for students lies elsewhere: in watching a careful mind gather reports, test rival theories, admit what puzzles him, and insist that a poetic phrase is not an explanation. For a classical Christian school it shows natural philosophy as patient attention to the created order, carried on by a pagan observer before the experimental method. The library attaches E. W. Webster's public-domain Oxford translation, divided into Books and Parts that follow the traditional chapters.
Top Lessons
A metaphor is not an explanation
When Empedocles called the sea 'the sweat of the earth', Aristotle granted that the phrase may satisfy a poem but said it fails as a scientific theory. The distinction runs through the Meteorology: Aristotle reports myths, poets and earlier philosophers with respect, then asks what each account actually explains and whether the facts agree. Students learn to love poetic language and still to ask, of any vivid phrase offered as an answer, what it claims and how one would know.
Deep time and the patience of observation
In Book I, Part 14, Aristotle argues that land and sea exchange places over spans too long for any human memory, so that whole peoples forget how their country began. He builds the case from evidence he can gather: the Nile's silt, a failed canal to the Red Sea, ships that can no longer sail into Lake Maeotis as they did sixty years before. Whatever one thinks of his conclusions, the method shows how small, measured changes can support large inferences, and how limited one lifetime is as a vantage on nature.
Testing theories against the facts
Aristotle's habit is to set out rival theories, then test each against what is observed. Against the Phaedo's single reservoir he objects that rivers would then flow up as much as down, and that every river is seen to end in the sea; he likens Democritus' prediction that the sea will dry up to one of Aesop's tales; on salt water he reports a small trial of his own. His conclusions are often mistaken, but students can see the shape of rational inquiry: state the view fairly, draw out its consequences, compare them with experience, and admit what remains obscure.
A thing is what it can do
Book IV ends with a principle Aristotle applies far beyond chemistry: what a thing is depends on its function. A dead man's hand is a hand only in name, like a stone flute or a wooden saw; an eye is an eye when it can see. The claim links the study of matter to the study of living things and prepares for the biological works. It also invites reflection on the purposes of human faculties and on why we speak of a body after death as no longer quite the person.
Verified Quotes
“There remains for consideration a part of this inquiry which all our predecessors called meteorology”
“the relation of land to sea changes too and a place does not always remain land or sea throughout all time”
“The whole land of the Egyptians, whom we take to be the most ancient of men, has evidently gradually come into existence and been produced by the river”
“But the theory of the Phaedo about rivers and the sea is impossible”
“Metaphors are poetical and so that expression of his may satisfy the requirements of a poem, but as a scientific theory it is unsatisfactory”
“Salt water when it turns into vapour becomes sweet, and the vapour does not form salt water when it condenses again. This I know by experiment”
“Tetanus and spasms are motions of wind, and their force is such that the united efforts of many men do not succeed in overcoming the movements of the patients”
“So we have only met with two instances of a moon rainbow in more than fifty years”
“Two of the qualities, the hot and the cold, are active; two, the dry and the moist, passive”
“Ripening is a sort of concoction; for we call it ripening when there is a concoction of the nutriment in fruit”
“What a thing is always determined by its function: a thing really is itself when it can perform its function; an eye, for instance, when it can see”
Medical Lens
The Meteorology repeatedly reasons by analogy between the earth and the animal body, which makes it a useful source for Greek physiological assumptions. Sweat and urine are said to carry the salty residue of undigested food; tremors, throbbing, tetanus and spasms are described as movements of wind (pneuma) in the body and used to explain earthquakes; and Book IV's doctrine of concoction, the perfecting of moisture by a thing's proper heat, is applied to boils and phlegm as well as to fruit and cooking, echoing the Hippocratic language of coction. These passages are analogies within a theory of nature, not clinical descriptions, and the physiology they presuppose is that of Aristotle's time.
- Book II, Part 3
Undigested residue of liquid food is salt and bitter; it is excreted in urine, which leaves a salt deposit in chamber-pots, and in sweat. Aristotle uses this to explain the saltness of the sea.
- Book II, Part 8
Earthquakes compared to the tremors and throbbings caused by wind in the body, including the shudder after passing water; tetanus and spasms described as motions of wind too strong for many men to restrain.
- Book IV, Parts 2–3
Concoction as the perfecting of moisture by natural heat; ripening extended to boils and phlegm, and rawness defined as imperfect concoction.
- Book IV, Part 12
A dead man is a man only in name, and his hand a hand only in name; a thing is itself when it can perform its function.