Thomasina: You can't stir things apart.
Septimus: No more you can, time must needs run backward, and since it will not, we must stir our way onward mixing as we go, disorder out of disorder into disorder until pink is complete, unchanging and unchangeable, and we are done with it forever. This is known as free will or self-determination. (1.1)
Septimus: "If everything from the furthest planet to the smallest atom of our brain acts according to Newton's law of motion, what becomes of free will?" (1.1)
Thomasina: If you could stop every atom in its position and direction, and if your mind could comprehend all the actions thus suspended, then if you were really, really good at algebra you could write the formula for all the future; and although nobody can be so clever as to do it, the formula must exist just as if one could. (1.1)