Mathematics is an obscure field, an abstruse science, complicated and exact; yet so many have attained perfection in it that we might conclude almost anyone who seriously applied himself would achieve a measure of success.
The men who administer public affairs must first of all see that everyone holds onto what is his, and that private men are never deprived of their goods by public men.
Things sacred should not only be touched with the hands, but unviolated in thought.
[Lat., Res sacros non modo manibus attingi, sed ne cogitatione quidem violari fas fuit.]
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 best Armour of Old Age is a well spent life preceding it; a Life employed in the Pursuit of useful Knowledge, in honourable Actions and the Practice of Virtue; in which he who labours to improve himself from his Youth, will in Age reap the happiest Fruits of them; not only because these never leave a Man, not even in the extremest Old Age; but because a Conscience bearing Witness that our Life was well-spent, together with the Remembrance of past good Actions, yields an unspeakable Comfort to the Soul
Wars, therefore, are to be undertaken for this end, that we may live in peace, without being injured; but when we obtain the victory, we must preserve those enemies who behaved without cruelty or inhumanity during the war.
For out of such an ungoverned populace one is usually chosen as a leader, someone bold and unscrupulous who curries favor with the people by giving them other men's property. To such a man the protection of public office is given, and continually renewed. He emerges as a tyrant over the very people who raised him to power.
What greater or better gift can we offer the republic than to teach and instruct our youth?
[Lat., Quod enim munus reiplicae afferre majus, meliusve possumus, quam si docemus atque erudimus juventutem?]