Plato's ontology

Plato's ontology was based on The Cave and human perception as only able to perceive shadows of Ideal Forms on the walls of this conceptual metaphor. It was a very major influence on all 20th century philosophy of mathematics and neoclassical philosophy.

It was embraced by Karl Popper even as he rejected the rest of Plato, it was bemusedly implied by Paul Erdos in his Erodisms, questioned by Eugene Wigner, and firmly rejected by Hilary Putnam and Michel Foucault.