To be philosophy's slave is to be free

How can intemperate minds be free when they're slaves to their own passions?

See, it's no in between: you're either free or you're a slave.

The highest form of slavery is to make the slave think that he is free.

He that is kind is free, though he is a slave; he that is evil is a slave, though he be a king.

We were born as a free soul. We only become enslaved in the world.