No one has ever learned fully to know themselves.

A noble person attracts noble people, and knows how to hold on to them.

The loss of a much-prized treasure is only half felt when we have not regarded its tenure as secure.

The most damaging prejudice consists of banning any kind of investigation of nature.

Happy is it, indeed, for me that my heart is capable of feeling the same simple and innocent pleasure as the peasant whose table is covered with food of his own rearing, and who not only enjoys his meal, but remembers with delight the happy days and sunny mornings when he planted it, the soft evenings when he watered it, and the pleasure he experienced in watching its daily growth.

Could we perfect human nature, we might also expect a perfect state of things.

When the boy begins to understand that the visible point is preceded by an invisible point, that the shortest distance between two points is conceived as a straight line before it is ever drawn with pencil and paper...the fountain of all thought has been opened to him...the philosopher can reveal him nothing new, as a geometrician he has discovered the basis of all thought.