Epictetus, Golden Sayings 19

. . . Something like that is what should pass between a teacher and ingenuous youths. As it is, what does pass? The teacher is a lifeless body, and you are lifeless bodies yourselves. When you have had enough to eat today, you sit down and weep about tomorrow's food. Slave! If you have it, well and good. If not, you will depart. The door is open—why lament? 

What further room is there for tears? What further occasion for flattery? Why should one envy another? Why should you stand in awe of them that have much or are placed in power, especially if they are also strong and passionate? 

Why, what should they do to us? What they can do, we will not regard. What does concern us, that they cannot do. Who then shall rule one that is thus minded?