A true understanding and humble estimate of oneself is the highest and most valuable of all lessons. To take no account of oneself, but always to think well and highly of others is the highest wisdom and perfection. Should you see another person openly doing evil, or carrying out a wicked purpose, do not on that account consider yourself better than him, for you cannot tell how long you will remain in a state of grace. We are all frail; consider none more frail than yourself.
—Thomas à Kempis, The Inner Life