In discussing time, Aristotle frequently mentions "the whole" and "the sphere itself." I have the intuition that it is related to his physical cosmology, but fail to see anything that clarifies this. I am particularly wondering what he means when he says "Some assert that [time] is the movement of the whole, others that it is the sphere itself" and "time is the sphere of the whole." What is he saying?
In the discussion about time in *Physics, bk IV, with "sphere of the whole", Aristotle is referring to the theory of Celestial spheres and in particular to the outermost one, that contains everything.
[§14, 223b13] time is measured by motion [...] time is thought to be the movement of the sphere, viz. because the other movements are measured by this, and time by this movement.