A careful physician . . . before he attempts to administer a remedy to his patient, must investigate not only the malady of the man he wishes to cure, but also his habits when in health, and his physical constitution.
Not to know what happened before you were born is to be a child forever. For what is the time of a man, except it be interwoven with that memory of ancient things of a superior age?
The most evident difference between man and animals is this: the beast, in as much as it is largely motivated by the senses and with little perception of the past or future, lives only for the present. But man, because he is endowed with reason by which he is able to perceive relationships, sees the causes of things, understands the reciprocal nature of cause and effect, makes analogies, easily surveys the whole course of his life, and makes the necessary preparations for its conduct.
All I can do is to urge on you to regard friendship as the greatest thing in the world; for there is nothing which so fits in with our nature, or is so exactly what we want in prosperity or adversity.
But as to the affection which anyone may have for us, it is the first demand of duty that we do most for him who loves us most; but we should measure affection, not like youngsters, by the ardour of its passion, but rather by its strength and constancy.