SPIRITUAL COMPLEMENT: The Heart of Christianity is a complementary work to SPIRITUAL SUBSTANCE, by the same author, and the second volume in the three book series: "The Heart of Christianity." It seeks to lead readers more deeply into the spiritual journey to holiness and union with God through Jesus Christ our Lord, while continuing to focus on what is most essential or fundamental in the spiritual life. Here again, you will find classic Catholic spirituality, strong and clear, for contemporary Christians.