Not a choice, but a Right

One way Spinoza explained this is best interpreted through this quote from Sophie's World. "You may have the right to move your thumb any way you choose. But your thumb can only move in according to its nature." In a similar analogy, I can roll and shift my eyes in any direction I choose, but due to the nature of the human body, I cannot pull out my eye, stick it in a hole I create in my palm and expect it to work the same. My body and mind are mine to utilize, but I will always be confined and limited by the specific parameters of my body's design.