[82] Aristot. De Animâ, II. vii. p. 419, a. 2-25; Aristot. De Sensu et Sensili, iv. p. 442, a. 20, — seven colours.
The same necessity for an intervening medium external to the subject, as in the case of vision, prevails also in the senses of hearing and smell. If the audible or odorous object be placed in contact with its organ of sense, there will be no hearing or smell. Whenever we hear or smell any object, there must be interposed between us and the object a suitable medium that shall be affected first; while the organ of sense will be affected secondarily through that medium. Air is the medium in regard to sound, both air and water in regard to smell; but there seems besides (analogous to the transparent in regard to vision) a special agency called the Trans-Sonant, which pervades air and enables it to transmit sound; and certainly another special agency called the Trans-Olfacient, which pervades both air and water, and enables them to transmit smell.[83] (It seems thus that something like a luminiferous ether — extended, mobile, and permeating bodies, yet still incorporeal in itself — was an hypothesis as old as Aristotle; and one other ether besides, analogous in property and purpose — an odoriferous ether; perhaps a third or soniferous ether, but this is less distinctly specified by Aristotle.)
[83] Aristot. De Animâ, II. vii. p. 419, a. 25-35; De Sensu et Sensili, v. p. 442, b. 30; Themistius ad Aristot. De Animâ, II. vii., viii. p. 115, Spengel. Of the three names, τὸ διαφανές — τὸ διηχές — τὸ δίοσμον, the last two are not distinctly stated by Aristotle, but are said to have been first applied by Theophrastus after him. See the notes of Trendelenburg and Torstrick; the latter supposes Themistius to have had before him a fuller and better text of Aristotle than that which we now possess, which seems corrupt. In our present text, the transparent as well as the trans-olfacient ether are clearly indicated, the trans-sonant not clearly.
Sound, according to Aristotle, arises from the shock of two or more solid bodies communicated to the air. It implies local movement in one at least of those bodies. Many soft bodies are incapable of making sound; those best suited for it are such as metals, hard in structure, smooth in surface, hollow in shape. The blow must be smart and quick, otherwise the air slips away and dissipates itself before the sound can be communicated to it.[84] Sound is communicated through the air to the organ of hearing; the air is one continuum (not composed of adjacent particles with interspaces), and a wave is propagated from it to the internal ear, which contains some air enclosed in the sinuous ducts within the membrane of the tympanum, congenitally attached to the organ itself, and endued with a certain animation.[85] This internal air within the ear, excited by the motion propagated from the external ear, causes hearing. The ear is enabled to appreciate accurately the movements of the external air, because it has itself little or no movement within. We cannot hear with any other part of the body; because it is only in the ear that nature has given us this stock of internal air. If water gets into the ear, we cannot hear at all; because the wave generated in the air without, cannot propagate itself within. Nor can we hear, if the membrane of the ear be disordered; any more than we can see, when the membrane of the eye is disordered.[86]
[84] Aristot. De Animâ, II. viii. p. 419, b. 4 seq. He calls air ψαθυρός, εὔθρυπτος (p. 420, a. 1-8), — εὐδιαίρετος, εὐόλισθος (Themistius, pp. 116, 117, Sp.) — “quod facilé diffluitâ€� (Trendelenburg, Comm. p. 384). He says that for sonorous purposes air ought to be ἀθροῦν — compact or dense: sound reverberates best from metals with smooth surface, p. 420, a. 25.
[85] Aristot. De Animâ, II. viii. p. 419, b. 34 seq.: οὗτος δ’ (ὁ ἀὴρ) ἐστὶν ὁ ποιῶν ἀκούειν, ὅταν κινηθῇ συνεχὴς καὶ εἷς· — ψοφητικὸν μὲν οὖν τὸ κινητικὸν ἑνὸς ἀέρος συνεχείᾳ μέχρις ἀκοῆς. ἀκοῇ δὲ συμφυὴς ἀήρ· διὰ δὲ τὸ ἐν ἀέρι εἶναι, κινουμένου τοῦ ἔξω τὸ εἴσω κινεῖ. διόπερ οὐ πάντῃ τὸ ζῷον ἀκούει, οὐδὲ πάντῃ διέρχεται ὁ ἀήρ· οὐ γὰρ πάντῃ ἔχει ἀέρα τὸ κινησόμενον μέρος καὶ ἔμψυχον. — διὰ τὰς ἕλικας (p. 420, a. 13).
The text of this passage is not satisfactory. It has been much criticised as well as amended by Torstrick; see his Comment. p. 148 seq. I cannot approve his alteration of ἔμψυχον into ἔμψοφον.
[86] Aristot. De Animâ, II. viii. p. 420, a. 9: ὁ δ’ ἐν τοῖς ὠσὶν ἐγκατῳκοδόμηται πρὸς τὸ ἀκίνητος εἶναι, ὅπως ἀκριβῶς αἰσθάνηται πάσας τὰς διαφορὰς τῆς κινήσεως. — p. 420, a. 14. οὐδ’ (ἀκούομεν) ἂν ἡ μήνιγξ κάμῃ, ὥσπερ τὸ ἐπὶ τῇ κόρῃ δέρμα ὅταν κάμῃ.
Voice is a kind of sound peculiar to animated beings; yet not belonging to all of them, but only to those that inspire the air. Nature employs respiration for two purposes: the first, indispensable to animal life, — that of cooling and tempering the excessive heat of the heart and its adjacent parts; the second, not indispensable to life, yet most valuable to the higher faculties of man, — significant speech. The organ of respiration is the larynx; a man cannot speak either when inspiring or expiring, but only when retaining and using the breath within. The soul in those parts, when guided by some phantasm or thought, impels the air within against the walls of the trachea, and this shock causes vocal sounds.[87]
[87] Aristot. De Animâ, II. viii. p. 420, b. 5-p. 421, a. 6. ὥστε ἡ πληγὴ τοῦ ἀναπνεομένου ἀέρος ὑπὸ τῆς ἐν τούτοις τοῖς μορίοις ψυχῆς πρὸς τὴν καλουμένην ἀρτηρίαν φωνή ἐστιν. οὐ γὰρ πᾶς ζῴου ψόφος φωνή, καθάπερ εἴπομεν (ἔστι γὰρ καὶ τῇ γλώττῃ ψοφεῖν καὶ ὡς οἱ βήττοντες) ἀλλὰ δεῖ ἔμψυχόν τε εἶναι τὸ τύπτον καὶ μετὰ φαντασίας τινός· σημαντικὸς γὰρ δή τις ψόφος ἐστὶν ἡ φωνή· καὶ οὐ τοῦ ἀναπνεομένου ἀέρος, ὥσπερ ἡ βήξ, ἀλλὰ τούτῳ τύπτει τὸν ἐν τῇ ἀρτηρίᾳ πρὸς αὐτήν.