Gradually the conviction gained recognition that all knowledge about things is exclusively a working-over of the raw material furnished by the senses. ... Galileo and Hume first upheld this principle with full clarity and decisiveness.
Friendship with the upright, with the truthful and with the well informed is beneficial. Friendship with those who flatter, with those who are meek and who compromise with principles, and with those who talk cleverly is harmful.
There are some with whom we may study in common, but we shall find them unable to go along with us to principles. Perhaps we may go on with them to principles, but we shall find them unable to get established in those along with us. Or if we may get so established along with them, we shall find them unable to weigh occurring events along with us.
A maxim is a conclusion upon observation of matters of fact, and is merely speculative; a "principle" carries knowledge within itself, and is prospective.
In a crystal we have clear evidence of the existence of a formative life principle, and though we cannot understand the life of a crystal, it is nonetheless a living being
it is not necessary to accept everything as true, one must only accept it as necessary.' 'A melancholy conclusion,' said K. 'It turns lying into a universal principle.
It is clear, then, that wisdom is knowledge having to do with certain principles and causes. But now, since it is this knowledge that we are seeking, we must consider the following point: of what kind of principles and of what kind of causes is wisdom the knowledge?
The so-called Pythagoreans, who were the first to take up mathematics, not only advanced this subject, but saturated with it, they fancied that the principles of mathematics were the principles of all things.