J. I. Packer states that language must be used in a stretched sense. God is not a sixteenth-century monarch, he says, and divine government is not the same as earthly government. He states that Christians should regard all truth of God as an "apprehended mystery," and always hold that God is greater than our formularies. He holds, nonetheless, that penal substitution can be described as a model in a way comparable to how physics uses the term. He defines the term model, in a theological sense, as "explanatory constructs formed to help us know, understand, and deal with God, the ultimate reality." He states that the "mystery of God is more than any one model, even the best, can express." He states that "all the knowledge we can have of the atonement is of a mystery which we can only think and speak by means of models." To Packer, the biblical models are presented as being inspired by God and given to us as "knowledge of the mystery of the cross." The theologian Stephen Sykes has interpreted Packer's account of penal substitution as being presented as a metaphor.