This is Valentines major apologetic work. In this book, Valentine defends a robust natural theology, arguing that Theism is the only rational worldview in contradistinction to the materialistic rationalism which pervaded the nineteenth century. Valentine stands within the nineteenth century apologetic tradition among the likes of B.B. Warfield an Charles Hodge. Though some of the science of this book is dated, this work still stands as a convincing rational defense of the Christian faith.