It is not proper for a man to accept as trustworthy anything other than one of these three things. The first is a thing for which there is a clear proof deriving from man’s reasoning—such as arithmetic, geometry, and astronomy. The second is a thing that a man perceives through one of the five senses—such as when he knows with certainty that this is red and this is black and the like through the sight of his eye; or as when he tastes that this is bitter and this is sweet; or as when he feels that this is hot and this is cold; or as when he hears that this sound is clear and this sound is indistinct; or as when he smells that this is a pleasing smell and this is a displeasing smell and the like. The third is a thing that a man receives from the prophets or from the righteous. Every reasonable man ought to distinguish in his mind and thought all the things that he accepts as trustworthy, and say: “This I accept as trustworthy because of tradition, and this because of sense-perception, and this on grounds of reason.” Anyone who accepts as trustworthy anything that is not of these three species, of him it is said: “The simple believes everything.”
—Maimonides (??? ?? ?????), Letter to the Community of Marseille (1194 CE)(R. Lerner transl.)
