Like all true followers of Kant, Riehl prefers epistemology to metaphysics; yet in reality he founds a metaphysics on epistemology, which he calls " critical realism," so far as it asserts a knowledge of things beyond phenomena, and " critical monism," so far as it holds that these things are unlike both physical and psychical phenomena, but are nevertheless the common basis of both.
This increases shelf life and keeps people from getting sick from spoiled juice, but it also kills the life-giving enzymes found in whole founds.
Attempts have been made, principally founded on some remarks of Huygens, to show that Descartes had learned the principles of refraction from the manuscript of a treatise by Willebrord Snell, but the facts are uncertain; and, so far as Descartes founds his optics on any one, it is probably on the researches of Kepler.
He founds his argument mainly on passages in the Communia Naturalium, which indeed prove distinctly that it was sent to Clement, and cannot, therefore, form part of the Compendium, as Brewer seems to think.
He founds his work upon that of his master Justin, but adds from his own knowledge among many other things, notably the detailed account of Valentinianism at the beginning of the book.