But the way in which this happens need not be known at this point it is enough that change in the eye does occur, whether because the muscles surrounding the eye press it or because the small nerves that correspond to the ciliary ligaments (which hold the crystalline lens suspended between the other humors of the eye) relax in order to increase the convexity of the crystalline lens and tighten to decrease it, or, finally, because the pupil dilates and contracts, for there are many people whose eyes undergo no other change.