Galen's Flat Lens

Nature is a self-sustaining cycle that slowly over time perfects itself into the most prominent equilibrium. Many of the pre-socratics philosophers connected the similarities between nature, and the balance of all things. This way of thinking was also adopted by the Greek philosopher Galen as well. The human eye is one keen example of how nature relates to balance, because of its ability to evolve into a shape that is best fit for vision. The shape of the lens in an eye - specifically humans - are an embodiment of nature, and its ability to adapt and change according to its surroundings and needs.

Objects are seen through the eyes by a multitude of straight lines of light. Therefore, a spherical shape for a lens would be simply bad design, because while that shape of that lens would have a lot of resistance, it lacked accuracy (On the usefulness of the parts, 470). In contrast, a flat surface for the lens would have more communicating points, but it would be far more prone to damage (On the usefulness of the parts, 502). Galen had dismissed the notion of a barrier protecting the flat lens due to the fact that it would most likely
Why, however, is this the case? Firstly, we must consider just how long ago life had started on the Earth, and in turn how long evolution has taken effect. Eyes on early hominins most likely would have been significantly differently, and possibly incapable of certain tasks. Although, nature has had time to create a balance of things through evolution; one being the eyesight of humans. Galen’s observation of how eye’s are “... a marvelous work of Nature’s …” (On the usefulness of the parts, 503), could be considered as an early insight to Charles Darwin's work on evolution almost seventeen hundred years later. This created optimal environments for not just humans, but for all