Sunshine and health / by Ronald Campbell MacFie.

  • Ronald Campbell Macfie
Date:
1927
Catalogue details

Licence: In copyright

Credit: Sunshine and health / by Ronald Campbell MacFie. Source: Wellcome Collection.

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    Sensation without actual material contact seemed to the Greek mind, as later on to New- ton, as inconceivable, and the theories of the Greek philosophers all tried to provide some intermediary between visible bodies and the eye. Briefly speaking, there were four dis- tinct theories. The first, held by Empedocles, Plato, and Hipparchus, supposed that some kind of ray projected from the sun and visible bodies met another ray projected from the eye -—as if two hands stretched out to touch each other. The second, taught by Epicurus and Lucretius, supposed that something went forth from the eye so that the eye touched visible bodies as we touch them by means of a stick. The third, Aristotle’s, held that light was the act or energy (energeia) of a transparent medium, and colour the act or energy of the transparent medium in so far as the medium wTas a constituent of coloured objects. The fourth, upheld by the Pythagoreans, main- tained that visible bodies emitted streams of fine particles which bombarded the eye. In very early times, too, the Greek mind busied itself with the astronomical side of light and, by aid of geometry and trigonometry, discovered many facts about the motion, dis- tance, and size of the heavenly bodies. More than a hundred years before Christ, Hip- parchus discovered the obliquity of the ecliptic