Baltasar Gracian (1601-1658) wrote many popular maxims:

33. Know when to put something aside– One of life’s great lessons lies in knowing how to refuse, and it is even more important to refuse yourself, both to business and to others…it is worse to busy yourself with the trivial than to do nothing…All excess is a vice, especially in your dealings with others.

51. Know how to choose– Most things in life depend on it. You need good taste and an upright judgment; intelligence and application are not enough…Two talents are involved: choosing and choosing the best.

89. Know yourself-– The key to everything.

104. Have a good sense of what each job requires-– “Far better are the jobs we don’t grow bored with, where variety combines with importance and refreshes our taste.”

110. Don’t wait to be a setting sun. Similar: Quit while you’re ahead; don’t wear out your welcome

121. Don’t make much ado about nothing-– “Few bothersome things are important enough to bother with…Many things that were something are nothing if left alone, and others that were nothing turn into much because we pay attention to them.” Similar: Take it easy.

139. Know your unlucky days – “On some days, everything goes badly; on others, well, and with less effort…Take advantage of such days, and don’t waste a moment of them.” (more…)