A man should always have these two rules in readiness. First, to do only what the reason of your ruling and legislating faculties suggest for the service of man. Second, to change your opinion whenever anyone at hand sets you right and unsettles you in an opinion, but this change of opinion should come only because you are persuaded that something is just or to the public advantage, not because it appears pleasant or increases your reputation.
Marcus AureliusIn the same degree in which a man's mind is nearer to freedom from all passion, in the same degree also is it nearer to strength.
Marcus AureliusRemember that man lives only in the present, in this fleeting instant; all the rest of his life is either past and gone, or not yet revealed.
Marcus Aurelius