The wise man must not abandon himself to sadness, nor give himself up to excessive joy; in all things he must preserve a perfect equilibrium of soul, and allow himself neither to be cast down by evils nor inflated by goods. For reason alone can give us tranquility; and reason is a sure guide, which never leads us astray, provided we know how to listen to it. But most men, carried away by their passions, let themselves be driven by every wind of desire or fear, and can never settle into a fixed and peaceful state. They are like the sea stirred by the winds, which has no rest; at times they are raised to the clouds by pride and vanity, at times plunged into the depths of discouragement by fear and grief. Thus, to be tranquil, one must first know what one wants, and propose a constant goal in all one's actions; for those who float and are uncertain of what they must do are always agitated and full of anxiety. One must then measure one's desires against one's strengths, and not undertake beyond what one can execute. For nothing troubles the soul more than to want what one cannot obtain, and to consume oneself in vain efforts for things that are beyond our reach. One must also remember that all the goods of life are fragile and uncertain, and that one must not attach oneself to them too strongly, lest their loss cause us unbearable pain. Finally, one must regard evils as inevitable, and bear them with patience, because it is useless to revolt against necessity. These are the principles that can give us tranquility of soul: but they are not enough by themselves; one must also put them into practice, and apply them to all the circumstances of life. For it is not enough to know what must be done, one must do it; and it is not enough to know the remedies, one must employ them. Thus, when you are attacked by some passion, whether of anger, sadness, fear, or desire, have recourse to reason, and ask it what must be done. It will answer you that anger is a madness that blinds, and that it must be repressed; that sadness is a weakness that casts down, and that it must be shaken off; that fear is an empty phantom that terrifies us, and that it must be despised; that desire is a fire that burns us, and that it must be extinguished. It will tell you further that the goods we pursue with so much ardor are often only disguised evils, and that the evils we flee with so much horror are often goods under a deceptive appearance. This is why one must never let oneself be carried away by one's impressions, but examine all things with a cool head, and judge only according to reason. If you wish to acquire this tranquility of soul, begin then by knowing yourself, and know what you are worth. Do not compare yourself to others, but to yourself; and if you are able to suffice unto yourself, you will be happy. For true happiness is in the soul, and not in external things; and tranquility is the fruit of wisdom, and not of fortune. Thus, cultivate your reason, and you will be tranquil; despise worldly goods, and you will be free; fear not death, and you will be invincible. These are the truths that we must meditate upon unceasingly, and that we must engrave in our hearts, if we wish to taste the sweetness of a peaceful and happy life.