P37: What is common to all things (on this see L2, above) and is equally in the part and in the whole, does not constitute the essence of any singular thing.

Dem.: If you deny this, conceive (if possible) that it does constitute the essence of some singular thing, say the essence of B. Then (by D2) it can neither be nor be conceived without B. But this is contrary to the hypothesis. Therefore, it does not pertain to the essence of B, nor does it constitute the essence of any other singular thing, q.e.d.