The Summary of Physics Restored

92Nature’s heat and Nature’s light are in reality the same, for they flow continually and uniformly from the same source, namely the Sun; but they are distinguished by their office. The task of heat is to penetrate nature’s inward parts, while light makes her outward parts manifest. Heat moves the hidden natures of things; light merely presents their perceptible accidents to the eyes. The Sun’s rays perform both. The Sun is therefore nature’s first instrument, by whose approach and retreat all nature’s operations are variously governed, intensified and abated through light and heat.