aristotle (384-322 bce)

metaphysica, physica, and de meteors. late 13th century

the titles of the three works contained in this medieval manuscript look easy to translate, but the modern connotations of metaphysics, physics and meteorology do not quite convey aristotle’s intent. the line between philosophy and science was not as firmly demarcated in the fourth century bce, when aristotle flourished, as it is today. in aristotle’s conception, physics was concerned with things which are ‘movable’ or ‘changeable’ and metaphysics with forces which are ‘immovable’ or ‘unchangeable’. meteorology was not just confined to the weather but took in the entire study of the earth and the oceans.

aristotle had remained a huge influence on european thought throughout the middle ages. the catholic church accepted his scientific treatises as doctrine. it was probably at the instigation of one of the church’s leading lights, thomas aquinas, that the dominican scholar william of moerbeke (now part of the belgian province of east flanders) translated all of aristotle’s surviving writings from greek to latin for wider distribution, in the thirteenth century. thought to have been made in paris by a near contemporary, this is a copy of william’s translation.

unlike the besancon missal or the rossdhu book of hours, it is not in itself a visually arresting work of art. sparing in the use of ornament and devoid of illustration, it was intended for scholarly use. the main text is written in dark brown ink in a long sloping hand, with occasional glosses appended in a very small, compact hand. the copious marginalia in light brown ink added sometime in the fourteenth century indicates how thoroughly aristotle’s words were scrutinised by scholars in the late medieval period.

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aristotle was born in stagira in north greece, the son of nichomachus, the court physician to the macedonian royal family. he was trained first in medicine, and then in 367bce he was sent to athens to study philosophy with plato. he stayed at plato’s academy until about 347.  pictured here with plato in raphael’s fresco, the school of athens. aristotle viewed the world quite differently, opposing plato’s main teachings, so when plato died, aristotle was not appointed head of the academy. after leaving athens, aristotle spent some time traveling, and possibly studying biology, in asia minor (now turkey) and its islands. he returned to macedonia in 338bce to tutor alexander the great; after alexander conquered athens, aristotle returned to athens and set up a school of his own, known as the lyceum. after alexander’s death, athens rebelled against macedonian rule, and aristotle’s political situation became precarious. to avoid being put to death, he fled to the island of euboea, where he died soon after.

aristotle is said to have written 150 philosophical treatises. the 30 that survive touch on an enormous range of philosophical problems, from biology and physics to morals to aesthetics to politics. many, however, are thought to be ‘lecture notes’ instead of complete, polished treatises, and a few may not be the work of aristotle but of members of his school.

the brief summary here outlines aristotle’s main contributons to science and philosophy: whereas aristotle’s teacher plato had located ultimate reality in ideas or eternal forms, knowable only through reflection and reason, aristotle saw ultimate reality in physical objects, knowable through experience. objects, including organisms, were composed of a potential, their matter, and of a reality, their form; thus, a block of marble – matter – has the potential to assume whatever form a sculptor gives it, and a seed or embryo has the potential to grow into a living plant or animal form. in living creatures, the form was identified with the soul; plants had the lowest kinds of souls, animals had higher souls which could feel, and humans alone had rational, reasoning souls. in turn, animals could be classified by their way of life, their actions, or, most importantly, by their parts.

though aristotle’s work in zoology was not without errors, it was the grandest biological synthesis of the time, and remained the ultimate authority for many centuries after his death. his observations on the anatomy of octopus, cuttlefish, crustaceans, and many other marine invertebrates are remarkably accurate, and could only have been made from first-hand experience with dissection. aristotle described the embryological development of a chick; he distinguished whales and dolphins from fish; he described the chambered stomachs of ruminants and the social organization of bees; he noticed that some sharks give birth to live young — his books on animals are filled with such observations, some of which were not confirmed until many centuries later.

aristotle’s classification of animals grouped together animals with similar characters into genera (used in a much broader sense than present-day biologists use the term) and then distinguished the species within the genera. he divided the animals into two types: those with blood, and those without blood (or at least without red blood). these distinctions correspond closely to our distinction between vertebrates and invertebrates. the blooded animals, corresponding to the vertebrates, included five genera: viviparous quadrupeds (mammals), birds, oviparous quadrupeds (reptiles and amphibians), fishes, and whales (which aristotle did not realize were mammals). the bloodless animals were classified as cephalopods (such as the octopus); crustaceans; insects (which included the spiders, scorpions, and centipedes, in addition to what we now define as insects); shelled animals (such as most molluscs and echinoderms); and ‘zoophytes,’ or ‘plant-animals,’ which supposedly resembled plants in their form — such as most cnidarians.

aristotle’s thoughts on earth sciences can be found in his treatise meteorology — the word today means the study of weather, but aristotle used the word in a much broader sense, covering, as he put it, ‘all the affections we may call common to air and water, and the kinds and parts of the earth and the affections of its parts.’ here he discusses the nature of the earth and the oceans. he worked out the hydrologic cycle: ‘now the sun, moving as it does, sets up processes of change and becoming and decay, and by its agency the finest and sweetest water is every day carried up and is dissolved into vapour and rises to the upper region, where it is condensed again by the cold and so returns to the earth.’ he discusses winds, earthquakes (which he thought were caused by underground winds), thunder, lightning, rainbows, and meteors, comets, and the milky way (which he thought were atmospheric phenomena). his model of earth history contains some remarkably modern-sounding ideas:

the same parts of the earth are not always moist or dry, but they change according as rivers come into existence and dry up. and so the relation of land to sea changes too and a place does not always remain land or sea throughout all time, but where there was dry land there comes to be sea, and where there is now sea, there one day comes to be dry land. but we must suppose these changes to follow some order and cycle. the principle and cause of these changes is that the interior of the earth grows and decays, like the bodies of plants and animals. . . .

 but the whole vital process of the earth takes place so gradually and in periods of time which are so immense compared with the length of our life, that these changes are not observed, and before their course can be recorded from beginning to end whole nations perish and are destroyed.

[he] believed that the universe never had a beginning and would never end; it was eternal. change, to aristotle, was cyclical: water, for instance, might evaporate from the sea and rain down again, and rivers might come into existence and then perish, in a continuous cycle.

in the later middle ages, aristotle’s work was rediscovered and enthusiastically adopted by medieval scholars. his followers called him ille philosophus (the philosopher), or ‘the master of them that know,’ and many accepted every word of his writings — or at least every word that did not contradict the bible — as eternal truth. fused and reconciled with christian doctrine into a philosophical system known as scholasticism, aristotelian philosophy became the official philosophy of the roman catholic church. as a result, some scientific discoveries in the middle ages and renaissance were criticized simply because they were not found in aristotle. source ucmp berkeley