.. we shall not be properly educated ourselves, nor will the guardians whom we are training, until we can recognise the qualities of discipline, courage, generosity, greatness of mind, and others akin to them, as well as their opposites in all their manifestations.
The science [geometry] is pursued for the sake of the knowledge of what eternally exists, and not of what comes for a moment into existence, and then perishes.
Any one who has common sense will remember that the bewilderments of the eyes are of two kinds, and arise from two causes, either from coming out of the light or from going into the light, which is true of the mind's eye, quite as much as of the bodily eye; and he who remembers this when he sees any one whose vision is perplexed and weak, will not be too ready to laugh; he will first ask whether that soul of man has come out of the brighter light, and is unable to see because unaccustomed to the dark, or having turned from darkness to the day is dazzled by excess of light.
A library of wisdom, is more precious than all wealth, and all things that are desirable cannot be compared to it. Whoever therefore claims to be zealous of truth, of happiness, of wisdom or knowledge, must become a lover of books.
So their combinations with themselves and with each other give rise to endless complexities, which anyone who is to give a likely account of reality must survey.
Such, Echecrates, was the end of our comrade, who was, we may fairly say, of all those whom we knew in our time, the bravest and also the wisest and most upright man.
If someone separated the art of counting and measuring and weighing from all the other arts, what was left of each (of the others) would be, so to speak, insignificant.
Those who are not schooled and practised in truth [who are not honest and upright men] can never manage aright the government, nor yet can those who spend their lives as closet philosophers; because the former have no high purpose to guide their actions, while the latter keep aloof from public life.