If someone is able to show me that what I think or do is not right, I will happily change, for I seek the truth, by which no one ever was truly harmed. Harmed is the person who continues in his self-deception and ignorance.

One of the recurring themes in Marcus' handbook is leadership's responsibility to work intelligently with what it is given and not waste time fantasizing about a world of flawless people and perfect choices.

Be not disgusted, nor discouraged, nor dissatisfied, if thou dost not succeed in doing everything according to right principles; but when thou bast failed, return back again, and be content if the greater part of what thou doest is consistent with man's nature, and love this to which thou returnest

A good man does not spy around for the black spots in others, but presses unswervingly on towards his mark.

Both happiness and unhappiness depend on perception

Whoever values peace of mind and the health of the soul will live the best of all possible lives.

Wilt thou, then, my soul, never be good and simple and one and naked, more manifest than the body which surrounds thee?