Those who believe that all virtue is to be found in their own party principles push matters to extremes; they do not consider that disproportion destroys a state.
If thinking is like perceiving, it must be either a process in which the soul is acted upon by what is capable of being thought, or a process different from but analogous to that. The thinking part of the soul must therefore be, while impassable, capable of receiving the form of an object; that is, must be potentially identical in character with its object without being the object. Mind must be related to what is thinkable, as sense is to what is sensible.
Our virtues are voluntary (and in fact we are in a sense ourselves partly the cause of our moral dispositions, and it is our having a certain character that makes us set up an end of a certain kind), it follows that our vices are voluntary also; they are voluntary in the same manner as our virtues.
The knowledge of the soul admittedly contributes greatly to the advance of truth in general, and, above all, to our understanding of Nature, for the soul is in some sense the principle of animal life.
There are three things that are the motives of choice and three that are the motives of avoidance; namely, the noble, the expedient, and the pleasant, and their opposites, the base, the harmful, and the painful. Now in respect of all these the good man is likely to go right and the bad to go wrong, but especially in respect of pleasure; for pleasure is common to man with the lower animals, and also it is a concomitant of all the objects of choice, since both the noble and the expedient appear to us pleasant.
When couples have children in excess, let abortion be procured before sense and life have begun; what may or may not be lawfully done in these cases depends on the question of life and sensation.
If the consequences are the same it is always better to assume the more limited antecedent, since in things of nature the limited, as being better, is sure to be found, wherever possible, rather than the unlimited.
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.