The separate self feels as though it is free to think and do as it pleases. But all its thoughts and actions arise from the ego thoughts in which it believes, and ego thoughts are not original; they are the thoughts of conditioned thinking. Although the separate self feels as though it has free will, it is actually under the tyranny of the ego.
Real thoughts are those that come from Self. Such thoughts represent our true will, which is free. The separate self cannot think such thoughts. In fact, the separate self cannot think at all—it can only think it thinks. That is part of the illusion.
There does exist one choice for the separate self, which is to accept the voice of Self instead of the tyrannical voice of the ego.
Even this choice is illusory, valid only within the illusion. The separate self is not separate from its source. The idea that there is a choice is the means by which within the dream of separation the mind can find its way back to what it never left.
“You have chosen to be in a state in opposition in which opposites are possible. As a result, there are choices you must make. In the holy state the will is free, so that its creative power is unlimited and choice is meaningless. Freedom to choose is the same power as freedom to create, but its application is different. Choosing depends on a split mind. The Holy Spirit is one way of choosing. God did not leave his children comfortless, even though they chose to leave Him. The voice they put in their minds was not the Voice for His Will, for which the Holy Spirit speaks.” (T-5.II.6)
“The ego cannot teach you anything as long as your will is free, because you will not listen to it. It is not your will to be imprisoned because your will is free. That is why the ego is the denial of free will. It is never God Who coerces you, because He shares His Will with you. His Voices teaches only in accordance with His Will, but that is not the Holy Spirit’s lesson because that is what you are. The lesson is that your will and God’s cannot be out of accord because they are one. This is the undoing of everything the ego tries to teach.” (T-8.II.3:1-8)