Abstract

A curious irony hangs over the two similes of the lantern and the clepsydra which Empedocles used to describe his theories of seeing and breathing. Similes were a feature of Empedocles' style, and it is clear that on these two in particular he has lavished considerable care. They have been preserved in their entirety, as almost the longest continuous quotations which Aristotle makes from any author. Despite such auspicious beginnings, these two similes have proved peculiarly resistant to modern attempts at interpretation. The reason for this, I shall try to show, is that certain features in the two similes took on a spurious significance as a result of Plato's remodelling of Empedocles' theories. Difficulties of interpretation have been caused by trying to read back these innovations of Platonic theory into details of the similes that in their original context were fortuitous and inessential.In Plato vision occurs when fire leaves the eye and joins fire outside to form a single compacted body, along which movements from the visible object are communicated as sensations to the eye.According to Theophrastus, Empedocles explained vision as the result of effluences which are given off from objects and enter the appropriate pores of the eye. Dark effluences enter the watery pores of the eyes, and bright effluences enter the fiery pores of the eye. As I have tried to show in an earlier article, Empedocles distinguished good and bad vision, by day and by night, for eyes with a predominance of fire and for eyes with a predominance of water. Good vision results when the dark and light elements which enter the eye are equally balanced. Poor vision results either when there is too much fire in the eye, so that we are dazzled, or when there is too much water in the eye, so that our vision is dimmed. In the whole of his detailed and one would have thought exhaustive account, Theophrastus says nothing about fire leaving the eye as a factor in the act of vision.