If you love knowledge, you will be a master of knowledge. What you have come to know, preserve by exercise; what you have not learned, seek to add to your knowledge; for it is as reprehensible to hear a profitable saying and not grasp it as to be offered a good gift by one's friends and not accept it. Spend your leisure time in cultivating an ear attentive to discourse, for in this way you will find that you learn with ease what others have found out with difficulty.

Verse 18. - To Demonicus