Ricoeur lectured and wrote for over twenty years on negation ('Do I understand something better if I know what it is not, and what is not-ness?') and never published his extensive writings on this subject. Ricoeur concluded that there are multiple forms of negation; it can, for example, be the other person (Plato), the not knowable nature of our world (Kant), the included opposite (Hegel), apophatic spirituality (Plotinus...