The Stoic Epictetus (50-130 AD) is a direct descendant of Socrates, the progenitor of the basic principles of psychotherapy and the "supplier" of ideas for monastic Christianity. His "Handbook" teaches philosophy as a way of everyday survival and virtue as a practical means of happiness. It is the teaching of a man who was born a slave but remained free, deprived of everything but remained happy. He does not preach revolution. His own life is revolutionary: it overturns, contemptuously, our entire system of values and motivations, mocking what is most dear or painful to us. He is indifferent to society - what he seeks is to elevate humanity.
There is no greater mystery than the mystery of the Good. And Epictetus is one of its initiates.