This treatise, published in 1669, is one of Owen's most popular and widely circulated writings. The purpose was to defend and uphold the doctrines of the Trinity and the Atonement, to refute current opponents and for "the edification and establishment of the plain Christian" such as "might be in danger to be seduced". The Trinity is considered two ways: according to its revelation and appearance in Scripture, and as it is further expressed and explained to guide the soul for greater edification. From discussing the Trinity, he moves to address the Person of Christ, followed by Christ's saving work of providing satisfaction for sin. The treatise is short, concise and has proved useful to many Christians over the years.