The philosopher and literary author Isaac Taylor (1787-1865) published this book anonymously in 1836. The work is a development of two earlier works: Saturday Evening (1832) and Natural History of Enthusiasm (1829), all three attempts to provide a philosophy to deal with the major problems and spiritual questions of the day. The popularity of Physical Theory led to Taylor relinquishing his previous anonymity. The work is a religious and philosophically speculative exploration of the possible paths of knowledge to information regarding the future existence of human beings. Taylor believed that knowledge of the human physical constitution could be used to conjecture information about the modes of human eternal life and eternity’s scheme of moral duties. The work was very popular among contemporaries and offers today an important insight into Victorian intellectual life. It is a rich source for historians of nineteenth-century religious philosophy.