Air possessed numerous and diverse properties; was eminently modifiable.
Air, life-giving and intelligent, existed everywhere, formed the essence of everything, comprehended and governed everything. Nothing in nature could be without it: yet at the same time all things in nature partook of it in a different manner.[185] For it was distinguished by great diversity of properties and by many gradations of intelligence. It was hotter or colder — moister or drier — denser or rarer — more or less active and movable — exhibiting differences of colour and taste. All these diversities were found in objects, though all at the bottom were air. Reason and intelligence resided in the warm air. So also to all animals as well as to men, the common source of vitality, whereby they lived, saw, heard, and understood, was air; hotter than the atmosphere generally, though much colder than that near the sun.[186] Nevertheless, in spite of this common characteristic, the air was in other respects so indefinitely modifiable, that animals were of all degrees of diversity, in form, habits, and intelligence. Men were doubtless more alike among themselves: yet no two of them could be found exactly alike, furnished with the same dose of aerial heat or vitality. All other things, animate and inanimate, were generated and perished, beginning from air and ending in air: which alone continued immortal and indestructible.[187]
[185] Diog. Ap. Fr. vi. καὶ ἐστι μηδὲ ἓν ὅ, τι μὴ μετέχει τούτου (air). Μετέχει δὲ οὐδὲ ἓν ὁμοίως τὸ ἕτερον τῷ ἑτέρῳ· ἀλλὰ πολλοὶ τρόποὶ καὶ αὐτοὺ τοῦ ἀέρος καὶ τῆς νοήσιός εἰσιν.
Aristotel. De Animâ, i. 2, p. 405, a. 21. Διογένης δ’, ὥσπερ καὶ ἑτεροί τινες, ἀέρα [ὑπέλαβε τὴν ψυχήν], &c.
[186] Diog. Ap. Fr. vi. καὶ πάντων ζώων δὴ ἡ ψυχὴ τὸ αὐτό ἐστιν, ἀὴρ θερμότερος μὲν τοῦ ἔξω ἐν ᾧ ἐσμέν, τοῦ μέντοι παρὰ τῷ ἡελίῳ πολλὸν ψυχρότερος.
[187] Diogen. Apoll. Fr. v. ch. 38, Panz.
Physiology of Diogenes — his description of the veins in the human body.
The intelligence of men and animals, very unequal in character and degree, was imbibed by respiration, the inspired air passing by means of the veins and along the blood into all parts of the body. Of the veins Diogenes gave a description remarkable for its minuteness of detail, in an age when philosophers dwelt almost exclusively in loose general analogies.[188] He conceived the principal seat of intelligence in man to be in the thoracic cavity, or in the ventricle of the heart, where a quantity of air was accumulated ready for distribution.[189] The warm and dry air concentrated round the brain, and reached by veins from the organs of sense, was the centre of sensation. Taste was explained by the soft and porous nature of the tongue, and by the number of veins communicating with it. The juices of sapid bodies were sucked up by it as by a sponge: the odorous stream of air penetrated from without through the nostrils: both were thus brought into conjunction with the sympathising cerebral air. To this air also the image impressed upon the eye was transmitted, thereby causing vision:[190] while pulsations and vibrations of the air without, entering through the ears and impinging upon the same centre, generated the sensation of sound. If the veins connecting the eye with the brain were inflamed, no visual sensation could take place;[191] moreover if our minds or attention were absorbed in other things, we were often altogether insensible to sensations either of sight or of sound: which proved that the central air within us was the real seat of sensation.[192] Thought and intelligence, as well as sensation, was an attribute of the same central air within us, depending especially upon its purity, dryness, and heat, and impeded or deadened by moisture or cold. Both children and animals had less intelligence than men: because they had more moisture in their bodies, so that the veins were choked up, and the air could not get along them freely to all parts. Plants had no intelligence; having no apertures or ducts whereby the air could pervade their internal structure. Our sensations were pleasurable when there was much air mingled with the blood, so as to lighten the flow of it, and to carry it easily to all parts: they were painful when there was little air, and when the blood was torpid and thick.[193]
[188] Diogen. Apoll. Fr. vii. ch. 48, Panz. The description of the veins given by Diogenes is preserved in Aristotel. Hist. Animal, iii. 2: yet seemingly only in a defective abstract, for Theophrastus alludes to various opinions of Diogenes on the veins, which are not contained in Aristotle. See Philippson, Ὕλη ἀνθρωπίνη, p. 203.
[189] Plutarch, Placit. Philos. iv. 5. Ἐν τῇ ἀρτηριακῇ κοιλίᾳ τῆς καρδίας, ἥτις ἐστὶ καὶ πνευματική. See Panzerbieter’s commentary upon these words, which are not very clear (c. 50), nor easy to reconcile with the description given by Diogenes himself of the veins.