Under that despotism of the eye (the emancipation from which Pythagoras by his numeral and Plato by his mystical symbols, and both by geometric discipline, aimed at, as the first propaideutikon of the mind)under this strong sensuous influence, we are restless because invisible things are not the objects of vision; and metaphysical systems, for the most part, become popular not for their truth, but in proportion as they attribute to causes a susceptibility of being seen, if only our visual organs were sufficiently powerful.

Samuel Taylor Coleridge, Biographia Literaria