'How does stoicism fit with non-duality?' Listener question

I’d love to hear your reflection on these teachings. They assume free will, duality, and mastery are our best intentions. 

When Seneca was an advisor to Nero, he served alongside an aide named Epaphroditus, the owner of a slave named…Epictetus.Yet between Seneca, who was the richest man in Rome, Epaphroditus, who was one of the most powerful men in Rome, and Epictetus, who as a slave had no power at allit would be the slave who was the most free.How could that possibly be?Seneca himself would say that to be free is to belong to yourself. It is to be in charge of your mind, your will, your self. It is to insulate yourself from pointless obligations, from other people’s expectations, from materialism and the slavery of cravings or aspirations.“Most powerful is he who has himself in his own power,” Seneca said.Seneca would know, for he was acutely aware that he lacked such power. So did Epictetus. Not only as a slave, but also as a witness to Nero slowly buying and trapping Seneca in a gilded cage. In the end, Seneca couldn’t even quit his job without permission. It was the ultimate prison—one with no walls.Seneca was not a singular figure in this regard. Epictetus saw countless other people who were unable to walk away from a job they hated because they were walled in by big houses and fancy titles. He saw people contorting themselves to get on Nero’s good side. He saw all the limitations and constraints that come with money and power. He saw how jobs that needed to be held for years in order to get ahead narrowed the choices of the ambitious who held them, like chains attached to their own yoke.Epictetus was horrified by what he saw. “It is better to starve to death in a calm and confident state of mind,” he would say, “than to live anxiously amidst abundance.”“Freedom is the prize we are working for,” Seneca wrote, “not being a slave to anything—not to compulsion, not to chance events.” Then he said, “show me a man who isn’t a slave.” To money. To work. To fear. To whatever everyone else is doing. To alcohol, to cigarettes, soda, material possessions, bad habits, followers on social media, anchors on cable news. Indeed, we have many masters.