Progress has not followed a straight ascending line, but a spiral with rhythms of progress and retrogression, of evolution and dissolution.

Superstition belongs to the essence of mankind and takes refuge, when one thinks one has suppressed it completely, in the strangest nooks and crannies; once it is safely ensconced there, it suddenly reappears.

We can't form our children on our own concepts; we must take them and love them as God gives them to us.

Microscopes and telescopes really confuse our minds.

We don't get to know anything but what we love.

Who is sure of their own motives can in confidence advance or retreat.

The philosophers must station themselves in the middle.