In regard to vision, Empedokles supposed that it was operated mainly by the fire or light within the eye, though aided by the light without. The interior of the eye was of fire and water, the exterior coat was a thin layer of earth and air. Colours were brought to the eye as effluvia from objects, and became apprehended as sensations by passing into the alternate pores or ducts of fire and water: white colour was fitted to (or in symmetry with) the pores of fire, black colour with those of water.[132] Some animals had the proportions of fire and water in their eyes better adjusted, or more conveniently located, than others: in some, the fire was in excess, or too much on the outside, so as to obstruct the pores or ducts of water: in others, water was in excess, and fire in defect. The latter were the animals which saw better by day than by night, a great force of external light being required to help out the deficiency of light within: the former class of animals saw better by night, because, when there was little light without, the watery ducts were less completely obstructed — or left more free to receive the influx of black colour suited to them.[133]
[132] Emp. Frag. v. 301-310, Karst. τό τ’ ἐν μήνιγξιν ἐεργμένον ὠγύγιον πῦρ, &c. Theophr. De Sensu, s. 7, 8; Aristot. De Sensu, c. 3; Aristot. De Gen. et Corrupt. i. 8.
[133] Theophrastus, De Sensu, s. 7, 8.
Senses of hearing, smell, taste.
In regard to hearing, Empedokles said that the ear was like a bell or trumpet set in motion by the air without; through which motion the solid parts were brought into shock against the air flowing in, and caused the sensation of sound within.[134] Smell was, in his view, an adjunct of the respiratory process: persons of acute smell were those who had the strongest breathing: olfactory effluvia came from many bodies, and especially from such as were light and thin. Respecting taste and touch, he gave no further explanation than his general doctrine of effluvia and pores: he seems to have thought that such interpenetration was intelligible by itself, since here was immediate and actual contact. Generally, in respect to all the senses, he laid it down that pleasure ensued when the matter which flows in was not merely fitted in point of structure to penetrate the interior pores or ducts (which was the condition of all sensation), but also harmonious with them in respect to elementary mixture.[135]
[134] Theophrast. De Sensu, s. 9-21.
Empedokles described the ear under the metaphor of σάρκινον ὄζον, “the fleshy branch.”
[135] Theophrast. De Sensu, s. 9, 10. The criticisms of Theophrastus upon this theory of Empedokles are extremely interesting, as illustrating the change in the Grecian physiological point of view during a century and a half, but I reserve them until I come to the Aristotelian age. I may remark, however, that Theophrastus, disputing the doctrine of sensory effluvia generally, disputes the existence of the olfactory effluvia not less than the rest (s. 20).
Empedokles declared that justice absolutely forbade the killing of anything that had life. His belief in the metempsychosis. Sufferings of life are an expiation for wrong done during an antecedent life. Pretensions to magic power.