It is the mark of an educated mind to expect that amount of exactness which the nature of the particular subject admits. It is equally unreasonable to accept merely probable conclusions from a mathematician and to demand strict demonstration from an orator.
There are branches of learning and education which we must study merely with a view to leisure spent in intellectual activity, and these are to be valued for their own sake; whereas those kinds of knowledge which are useful in business are to be deemed necessary, and exist for the sake of other things.
The activity of God, which is transcendent in blessedness, is the activity of contemplation; and therefore among human activities that which is most akin to the divine activity of contemplation will be the greatest source of happiness.
Anything that we have to learn to do we learn by the actual doing of it; People become builders by building and instrumentalists by playing instruments. Similarily, we become just by performing just acts, temperate by performing temperate ones, brave by performing brave ones.
Hence intellect[ual perception] is both a beginning and an end, for the demonstrations arise from these, and concern them. As a result, one ought to pay attention to the undemonstrated assertions and opinions of experienced and older people, or of the prudent, no less than to demonstrations, for, because the have an experienced eye, they see correctly.
...one Greek city state had a fundamental law: anyone proposing revisions to the constitution did so with a noose around his neck. If his proposal lost he was instantly hanged.
If, then, there is some end of the things we do, which we desire for its own sake (everything else being desired for the sake of this), and if we do not choose everything for the sake of something else (for at that rate the process would go on to infinity, so that our desire would be empty and vain), clearly this must be the good and the chief good.
Because the rich are generally few in number, while the poor are many, they appear to be antagonistic, and as the one or the other prevails they form the government. Hence arises the common opinion that there are two kinds of government - democracy and oligarchy.
There is only one condition in which we can imagine managers not needing subordinates, and masters not needing slaves. This condition would be that each (inanimate) instrument could do its own work.
Between friends there is no need for justice, but people who are just still need the quality of friendship; and indeed friendliness is considered to be justice in the fullest sense.