An ambulance just sped by my house, sirens n all, and as it got further and further away, the sound of the siren got less and less distinct. During that time...there was a moment where I doubted myself: could I really still hear the siren, or was it just in my head? It got me thinking. Is knowledge absolute? Are things either true or false, black and white?...in a world of absolutes...can shades of gray in knowledge even exist?