[T]he first philosophers, in investigating the truth and the nature of things, wandered, as if led by ignorance, into a certain... path. Hence, they say that no being is either generated or corrupted, because it is necessary that what is generated should be generated either from being or non-being: but both these are impossible; for neither can being be generated, since it already is; and from nothing, nothing can be generated... And thus... they said that there were not many things, but that being alone had a subsistence. ...the ancient philosophers ...through this ignorance added so much to their want of knowledge, as to fancy that nothing else was generated or had a being; but they subverted all generation.

This opinion... appears to be ancient... that the one, excess and defect, are the principles of things... It is not... probable that there are more than three principles... [E]ssence is one certain genus of being: so that principles will differ from each other in prior and posterior alone, but not in genus, for in one genus there is always one contrariety, and all contrarieties appear to be referred to one. That there is neither one element, therefore, nor more than two or three, is evident.

Philosophy is the science of truth.

And surely to know what this good is, is of great importance for the conduct of life, for in that case we shall be like archers shooting at a definite mark, and shall be more likely to do what is right. But, if this is the case, we must try to comprehend, in outline at least, what it is and to which of the sciences it belongs.

Homer has taught all other poets the art of telling lies skillfully.

And happiness is thought to depend on leisure; for we are busy that we may have leisure, and make war that we may live in peace.

After these matters we ought perhaps next to discuss pleasure. For it is thought to be most intimately connected with our human nature, which is the reason why in educating the young we steer them by the rudders of pleasure and pain; it is thought, too, that to enjoy the things we ought and to hate the things we ought has the greatest bearing on virtue of character. For these things extend right through life, with a weight and power of their own in respect both to virtue and to the happy life, since men choose what is pleasant and avoid what is painful; and such things, it will be thought, we should least of all omit to discuss, especially since they admit of much dispute.

The best friend is he that, when he wishes a person's good, wishes it for that person's own sake.

When people are friends, they have no need of justice, but when they are just, they need friendship in addition.

Therefore only an utterly senseless person can fail to know that our characters are the result of our conduct.