We praise a man who feels angry on the right grounds and against the right persons and also in the right manner at the right moment and for the right length of time.

Men regard it as their right to return evil for evil and, if they cannot, feel they have lost their liberty.

It is the activity of the intellect that constitutes complete human happiness - provided it be granted a complete span of life, for nothing that belongs to happiness can be incomplete.

A friend is another I.

Thus then a single harmony orders the composition of the whole...by the mingling of the most contrary principles.

It is the mark of an educated mind to rest satisfied with the degree of precision which the nature of the subject admits and not to seek exactness where only an approximation is possible.

We do not know a truth without knowing its cause.