Without minimizing the validity of the social, political, and ecclesiastical approaches to this field of study, Yuille affirms that the essence of Puritanism is found in its spirituality. He demonstrates this by turning to a relatively unknown Puritan, George Swinnock (1627-1673).
At the root of Swinnock's spirituality was his concept of fear of God as the proper ordering of the soul's faculties after the image of God. This concept is pivotal to Swinnock's spirituality, because he viewed it as the Christian's true principles of practice. Yuille shows the prevalence of this paradigm among Swinnock's fellow Puritans, and sets it in a historical tradition extending back to Augustine through Calvin.