THE ASTROLOGIZATION OF THE ARISTOTELIAN COSMOS: CELESTIAL INFLUENCES ON THE SUBLUNARY WORLD IN ARISTOTLE, ALEXANDER OF APHRODISIAS, AND AVERROES
Gad Freudenthal*
. The changing role of the celestial influences on the sublunary world from Aristotle to Averroes
One of the radical and long-lived innovations of Aristotle’s physical world-picture was the introduction of the fifth substance. At an early phase of his development (reflected in his lost dialogue De philosophia), Aristotle still followed the Presocratics in believing in the essential mate- rial unity of the cosmos, and specifically held that the heavens were fiery. However, in his esoteric writings, those that are the core of what we con- strue as the mature Aristotle, the Stagirite introduced a decisive rupture of the universe by positing what later generations were to call “the fifth body” or “ether.” This newly fathomed celestial matter was quality-less and impassive and, hence, in principle, a “stranger to generation and destruction” (Solmsen , ). Considered from the vantage point of his theory of matter alone, the sublunary world was now a closed system whose functioning depended solely on the laws of physics bearing on the bodies constituted of the four sublunary elements.1 Yet, Aristotle was well aware that the sublunary world was not entirely self-sufficient, for obviously the Sun warmed it. As is well known, Aristo- tle explained the Sun’s heat through two ad hoc “mechanical” hypotheses: one states that the Sun warms by virtue of the friction between it and the air underneath; the other affirms that the heat is generated because the Sun’s movement scatters the elemental fire which is in contact with the celestial sphere. Aristotle offered two versions of this accountDe ( caelo
* CNRS, Paris. 1 I described this development in Freudenthal () , where further literature is indicated. gad freudenthal
.; Meteor. ., a–); but, as one scholar has justly commented, they are “both almost equally lame.”2 Aristotle posits one major effect of the superlunary world on the sublu- nary one: the efficient cause of all generation and corruption in the sub- lunary world is identified as the Sun’s double motion along the ecliptic (De gen. et corr. .–), since this motion brings about the seasons and keeps the four elements from settling into four stable, changeless, con- centric spherical layers (cf. De caelo ., b–). Aristotle, therefore, considers the heavenly bodies to be the ultimate source of all motion and change in the sublunary world (Meteor. ., a–) and holds that “in dependence on it [= the heavens as a whole] all other things have their existence and their life, some more directly, others more obscurely” (De caelo ., a–; trans. Guthrie ).3 Aristotle occasionally alludes to specific phenomena instantiating this principle. On the level of non- animate nature, we may mention the change of land into sea and vice versa, which is an “orderly” phenomenon produced by the “Sun’s course” (Meteor. ., esp. a–); and the two exhalations and their vari- ouseffectssuchasthephenomenawhichtakeplaceintheupperatmo- sphere (Meteor. ., esp. a) as well as winds, rainfall, and so forth, whichalsogobacktotheSun’swarmingeffect(Meteor. .). On the level of animate phenomena, there is most famously the fact that “a human beingisproducedbyahumanbeingandtheSun.”4 “Spontaneous” gen- eration too is held to be brought about by the Sun’s heat and the duration of gestation and of the length of the life of animal species is also taken to depend on celestial motions.5 Some natural phenomena (e.g., the time of menses) Aristotle similarly describes as depending specifically on the Moon’s motion.6 All these natural phenomena are said to have the orderly
2 Longrigg () ; see also Moraux () coll. –. 3 Quoted approvingly by Alexander, De providentia, (Thillet , .–; Fazzo and Zonta , ). For a penetrating analysis of Aristotle’sviews of the heavenly bodies as exerting σωτηρ α over the existents in the sublunary world, see Rashed (). 4 Phys. ., b; Meta. ., a; De gen. an. ., b. I quote the elegant (and politically correct) translation in Sharples (b) . Oehler () has convincingly argued that the purpose of this statement is to remind the reader of the Sun’s crucial role in continually mixing up the four sublunary elements, thereby producing the continued coming-to-be and passing-away; it has nothing to do with any ideas on the vivifying effect of the celestial bodies or of their heat. See also Freudenthal () –. 5 On spontaneous generation, see Freudenthal () (and index s.v.); on length of life, see De gen. an. ., bff. For further references and discussion, see Happ () –. 6 E.g., De gen. an. ., aff.; see also Préaux (), notably –, .