No tree which the wind does not often blow against is firm and strong; for it is stiffened by the very act of being shaken, and plants its roots more securely: those which grow in a sheltered valley are brittle: and so it is to the advantage of good men, and causes them to be undismayed, that they should live much amidst alarms, and learn to bear with patience what is not evil save to him who endures it ill.
