This curious little treatise is obviously un-Aristotelian, although the author is familiar, up to a point, with many of Aristotle’s views. It appears to be a philosophical rather than a medical document; its tentative manner makes a remarkable contrast with the extreme dogmatism of the pseudo-Hippocratic On Breaths (περὶ φυσῶν).
It has caused much difficulty to editors and translators. The text, though much improved by Jaeger and others, is very uncertain; there is a general lack of coherence in the thought; and there are two important and recurrent ambiguities of meaning. The first lies in the word πνεῦμα itself. The author seems to have grasped something of the Aristotelian theory of σύμφυτον πνεῦμα (see Introduction to On Length and Shortness of Life, p. 391), and frequently uses the phrase, varying it at times by the apparently equivalent expressions ἔμφυτον πνεῦμα and φυσικὸς ἀήρ; but it is often uncertain whether he is speaking of πνεῦμα in this technical sense or of ordinary breath, and he seems to confuse the two in his own mind. In the second place he makes frequent use of the word ἀρτηρία (translated “air-duct”). This word applies primarily (in Aristotle’s genuine works always) to the windpipe, and in several passages here (e.g., 481 a 22, b 13) quite clearly refers to it; elsewhere
(e.g., 484 a 14) it seems to be used of any duct; elsewhere again (e.g., 484 a 1) it apparently refers to the arteries, though without any realization that they are blood-vessels.
There are many other minor puzzles and inconsequentialities which still resist interpretation; and even to notice them lies beyond the scope of this series. It has seemed best to give the reader a fairly literal rendering of the best text as yet available, and to leave the problems open for discussion.