Baltasar Gracián is a man of the 17th century,
who wrote a good book called "The Oracle, a Manual of the Art
of Discretion" or translated liberally and commonly, "The
Art of Worldly Wisdom". He's like the
Confucius of Christianity, 
. Highly recommended to be in any religious
library.
Examples:
Aphorism #24
Keep the Imagination under control; sometimes correcting,
sometimes assisting it. For it is all-important for our happiness,
and even sets the reason right. It can tyrannise, and is not
content with looking on, but influences and even often dominates
life, causing it to be happy or burdensome according to the folly
to which it leads. For it makes us either contented or discontented
with ourselves. Before some it continually holds up the penalties
of action, and becomes the mortifying lash of these fools. To
others it promises happiness and adventure with blissful delusion.
It can do all this unless the most prudent self-control keeps it in
subjection.
Aphorism #109
Be not censorious. There are men of gloomy character who regard
everything as faulty, not from any evil motive but because it is
their nature to. They condemn all: these for what they have done,
those for what they will do. This indicates a nature worse than
cruel, vile Indeed. They accuse with such exaggeration that they
make out of motes beams wherewith to force out the eyes. They are
always taskmasters who could turn a paradise into a prison; if
passion intervenes they drive matters to the extreme. A noble
nature, on the contrary, always knows how to find an excuse for
failings, if not in the intention, at least from oversight.
Aphorism #105 Don't be a Bore.
The man of one business or of one topic is apt to be heavy. Brevity
flatters and does better business; it gains by courtesy what it
loses by curtness. Good things, when short, are twice as good. The
quintessence of the matter is more effective than a whole farrago
of details. It is a well-known truth that talkative folk rarely
have much sense whether in dealing with the matter itself or its
formaltreatment. There are that serve more for stumbling-stones
than centrepieces, useless lumber in every one's way. The wise
avoid being bores, especially to the great, who are fully occupied:
it is worse to disturb one of them than all the rest. Well said is
soon said.