"The rule of friendship means there should be mutual sympathy between them, each supplying what the other lacks and trying to benefit the other, always using friendly and sincere words."
"What is morally wrong can never be advantageous, even when it enables you to make some gain that you believe to be to your advantage. The mere act of believing that some wrongful course of action constitutes an advantage is pernicious."
"O philosophy, life's guide! O searcher-out of virtue and expeller of vices! What could we and every age of men have been without thee? Thou hast produced cities; thou hast called men scattered about into the social enjoyment of life."
"The life of the dead is placed in the memory of the living."
"A room without books is like a body without a soul."
"What sweetness is left in life, if you take away friendship? Robbing life of friendship is like robbing the world of the sun. A true friend is more to be esteemed than kinsfolk."