Other relaxations are peculiar to certain times, places and stages of life, but the study of letters is the nourishment of our youth, and the joy of our old age. They throw an additional splendor on prosperity, and are the resource and consolation of adversity; they delight at home, and are no embarrassment abroad; in short, they are company to us at night, our fellow travelers on a journey, and attendants in our rural recesses.
All the arts, which have a tendency to raise man in the scale of being, have a certain common band of union, and are connected, if I may be allowed to say so, by blood-relationship with one another.
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.
The following passage is one of those cited by Copernicus himself in his preface to De Revolutionibus: "The Syracusan Hicetas, as Theophrastus asserts, holds the view that the heaven, sun, moon, stars, and in short all of the things on high are stationary, and that nothing in the world is in motion except the earth, which by revolving and twisting round its axis with extreme velocity produces all the same results as would be produced if the earth were stationary and the heaven in motion. . . ."
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.
Lay down this rule of friendship: neither ask nor consent to do what is wrong. The plea, 'for friendship's sake,' is a discreditable one, and should not be admitted for a moment. We should ask from friends and do for friends only what is good.
The beauty of the world and the orderly arrangement of everything celestial makes us confess that there is an excellent and eternal nature, which ought to be worshiped and admired by all mankind.
We should never so entirely avoid danger as to appear irresolute and cowardly; but, at the same time, we should avoid unnecessarily exposing ourselves to danger, than which nothing can be more foolish.