THE OPTICAL TREATISE
FOOTNOTES
1. Cf. Shakespeare, Two Gentlemen of Verona II.iv.192: "Even as one heat another heat expels, Or as one nail by strength drives out another, So the remembrance of my former love Is by a newer object quite forgotten."
2. The Latin is lucidum, meaning something which shines by its own light, or is luminous. In order to avoid the cumbersome periphrasis ‘something which is luminous’, I translate it as ‘luminous body’. The word ‘body’ is not in Hobbes’s Latin here, except in the last sentence of Proposition 1.
3. The medical terms for the rhythmic contraction and expansion of the heart.
4. The text appears to be corrupt here, but the meaning is clear. The motion in the eye stimulates a ‘conation’ or microscopic motion in the retina, which then propagates the motion to the brain via the optic nerve.