A GOOD eye must be good to see whatsoever is to be seen, and not green things only. For that is proper to sore eyes. So must a good ear, and a good smell be ready for whatsoever is either to be heard, or smelt: and a good stomach as indifferent to all kinds of food, as a millstone is, to whatsoever she was made for, to grind. As ready therefore must a sound understanding be for whatsoever shall happen. But he that saith, O that my Children might live! and, O that all men might commend me for whatsoever I do! is an eye that seeks after green things; or as teeth, after that which is tender.
MARCUS AURELIUS. MEDITATIONS. Book x. 25.