Rudolf Steiner: "Freedom can be proved quite clearly if the proofs are sought on this basis: — That the world given to us as a perception is a mirrored reflection and not a reality.... We are free human beings because we carry out actions under the influence of Maya, and because this Maya, or the world immediately around us, cannot bring about or cause anything. Our freedom is based on the fact that the world that we perceive is Maya. The human being united himself in wedlock with Maya, and thus becomes a free being. If the world that we perceive were a reality, this reality would compel us, and we would not be free. We are free beings just because the world which we perceive is not a reality and for this reason it cannot force us to do anything, in the same way in which a mirrored reflection cannot force us to run away. The secret of the free human being consists in this: to realize the connection of the world perceived as Maya — the mere reflection of a reality — and the impulses coming from man himself. The impulses must come from man himself, when he is not induced to an action by something that influences him."
Thank you, Chris Manvell!