(Chapter 32) Footnote 15:

This section is revised as follows in the 1555 edition: “The patella is made so that the femur will be less easily dislocated to the anterior in flexion of the tibia or knee. But it will be correctly shown that this use of the patella, which is the only one anatomists are seen to have granted it, is secondary, if one ponders carefully how it provides for the strength of the very strong tendon to which it is attached whenever the knee is flexed deeply; the tendon would have to be pushed from the femur as it projected forward if the patella did not with its hardness take the pressure and the hard contact of the femur and receive it without harm, having the same function as many other sesamoid ossicles that we agree the Maker of things constructed.”