Philip K Dick - his 2 basic topics

Philip K Dick said in his paper "How to Build a Universe That Doesn't Fall Apart Two Days Later" that "two certain matters absolutely fascinate me, and that I write about them all the time. The two basic topics that fascinate me are "What is reality?" and "What constitutes the authentic human being?" Over the twenty-seven years in which I have published novels and stories I have investigated those two interrelated topics over and over again. I consider them important topics. What are we? What is it that surrounds us, that we call the not-me, or the empirical or phenomenal world?"

great questions and ones which I'm sure many people have wondered.