To realize that our knowledge is ignorance, This is a noble insight. To regard our ignorance as knowledge, This is mental sickness. Only when we are sick of the sickness Shall we cease to be sick. The Sage is not sick, being sick of sickness; This is the secret of health.
The science [geometry] is pursued for the sake of the knowledge of what eternally exists, and not of what comes for a moment into existence, and then perishes.
As the biggest library if it is in disorder is not as useful as a small but well-arranged one, so you may accumulate a vast amount of knowledge but it will be of far less value than a much smaller amount if you have not thought it over for yourself.
The superior student listens to the Way and follows it closely. The average student listens to the Way and follows some and some not. The lesser student listens to the Way and laughs out loud. If there were no laughter it would not be the Way.