Book Talk Tuesday, Introduction to the Devout Life, Part 3, Chapter 39
CHAPTER XXXIX. The Sanctity of the Marriage Bed.
THE marriage bed should be undefiled, as the Apostle tells us, 
i.e. pure, as it was when it was first instituted in the earthly
Paradise, wherein no unruly desires or impure thought might enter. All
that is merely earthly must be treated as means to fulfil the end God
sets before His creatures. Thus we eat in order to preserve life,
moderately, voluntarily, and without seeking an undue, unworthy
satisfaction therefrom. “The time is short,” says S. Paul; “it
remaineth that both they that have wives be as though they had not, and
they that use this world, as not abusing it.” 
Let every one, then, use this world according to his vocation, but so
as not to entangle himself with its love, that he may be as free and
ready to serve God as though he used it not. S. Augustine says that it
is the great fault of men to want to enjoy things which they are only
meant to use, and to use those which they are only meant to enjoy. We
ought to enjoy spiritual things, and only use those which are material;
but when we turn the use of these latter into enjoyment, the reasonable
soul becomes degraded to a mere brutish level.
 Heb. xiii. 4.
 1 Cor. vii. 30, 31.