I think one of the most comprehensive lessons on the nature of life are from the teachings of Dalai Lama. You'll see most philosophers going nuts, they choose words difficult to understand and metaphors hard to comprehend. The simplicity of these lessons is what makes them enlighten one's soul, while they still keep a practical tone. Many famous people praised Dalai Lama for his works and teachings. I won't have to explain any one of them, they are already in plain, simple English. Dalai Lama is the leader of the Yellow Hat sect of Buddhism, these teachings are not the work of one man man but many. My advice to you would be that you bookmark this page or write these down on a piece of paper.