I need to answer what the philosophical views of Descartes' pyramid and Peirce's raft have to do with the nature...

I need to answer what the philosophical views of Descartes' pyramid and Peirce's raft have to do with the nature of knowledge and what I think about it? It's a 2-3 page paper about your own opinion on what these images have to do with knowledge and my professor asked that we don't reference Descartes or Peirce.