How what is good in its own nature can be distinguished from other things that are good.
AND this may be distinguished from those other things which we have termed indifferent, in these ways: if a thing is good
in itself and not by reason of something else: if it is useful for its own sake, and not for the sake of something else: if
it is unchangeably and at all times good, and always keeps its character and can never become anything different: if its removal
or cessation cannot fail to produce the greatest harm: if that which is its opposite is in the
same way evil in its own nature, and can never be turned into anything good. And these descriptions by which the nature
of things that are good in themselves can be distinguished, cannot possibly be applied to fasting, for it is not good of itself,
nor useful for its own sake because it is wisely used for the acquisition of purity of heart and body, that the pricks of
the flesh being dulled the soul may be pacified and reconciled to its Creator, nor is it unchangeably and at all times good,
because often we are not injured by its intermission, and indeed sometimes if it is unreasonably practised it becomes
injurious. Nor is that which seems its opposite evil in its own nature, i.e., the partaking of food, which is naturally agreeable,
which cannot be regarded as evil, unless intemperance and luxury or some other faults are the result; "For not that which
entereth into the mouth, defileth a man, but that which cometh out of the mouth, that defileth a man."11091109
And so a man disparages what is good in its own nature, and does not treat it properly or without sin, if he does it not
for its own sake but for the sake of something else, for everything else should be done for the sake of it, but it should
be sought for its own sake alone.