So, philosophers haven't reflected on negative concepts in depth:
- because they are useless;
- because they are a little scary (what about nothingness being the ground of things!, what about everything being useless!);
- because it is difficult to study them (it is not easy to determine the Impossible and show the great effects of Non-Doing).
__Giovanni Papini, L'altra metà (1911), 2: The Other Half