For those, of all ages, who may have wondered but not inquired, and who retain a niggling disquiet at their own uncertainty, it is hoped that reading this book will suggest a superordinate structure, where doubts and uncertainties will disappear and an awareness of wonder and personal enlightenment will prevail. This book would also be appropriate for younger students in schools and colleges as an orientation study of various thinkers who have attempted to understand what it is to be human and how we understand the world we exist in.