LCL 288: 392-393
aether of the De Caelo, where we are told that it is ungenerated, indestructible and divine, and endowed with circular motion (269 a 31, 270 a 12, b 10, 289 a 15). It would seem, then, that πνεῦμα is found in all liquids; it is characterized by heat and (perhaps) foam or froth; it is associated with boiling (479 b 32); it forms a link between the immaterial and the material; and it is a kind of motive force. All this suggests something very like steam, or perhaps the capacity of liquid to be evaporated and expanded by heat.a
At any rate the pulsation of the heart and blood-vessels is attributed by Aristotle to the aeration or pneumatization of the liquid food as it reaches the heart and is converted into blood, and is expanded by the intense soul-heat which is concentrated in that region. Probably the expansion is conceived as spasmodic, being continually checked as fresh supplies of cold liquid food arrive; but the theory may have been suggested by the vibration of a cooking-vessel when liquid is boiled in it.
In spite of its many shortcomings and obvious errors, it is difficult not to be impressed by the ingenuity of Aristotle’s physiological theory. The wonder is, not that he made mistakes, but that so
- aOf course this applies only to the physical conception of πνεῦμα. No doubt the term had many primitive associations of a religious and semi-mystical character. The doctrine of Pneumatism has been discussed at length by Wellman: “Die pneumatische Schule bis auf Archigenes” (Phiologische Untersuchungen xiv. (1895), Jaeger: “Das Pneuma im Lykeion” (Hermes xlviii. (1913), pp. 29-74 and Allbutt: Greek Medicine in Rome (1921), pp. 224 ff. All these accounts tend to go beyond the evidence and should be accepted with caution.
many of his conjectures, often made with very imperfect opportunities for observation, came so near to the truth. We are still unable to judge with any certainty how much of his teaching on this subject was original and how much was merely a synthesis of existing doctrines; but at least he must have the credit of having set out a fairly coherent system. If later and lesser thinkers, by attributing to his doctrines a finality which they did not deserve, hindered rather than helped the advance of knowledge, it is surely unfair to hold Aristotle himself responsible.