This work examines the problem of how to connect the historic doctrine of the Trinity to Christian devotional practice. Two criteria for a successful Trinitarian spirituality are proposed: that of drawing significantly from nuances of the classic formulations of the doctrine and dealing with the mode of original Trinitarian self-disclosure, that is, the unfolding biblical doctrine of the historia salutis. Various historical attempts at articulating a method are examined, with special emphasis given to the Puritan John Owen. ""In this work, Brian Kay has opened up new possibilities in understanding John Owen for our day. By showing how Owen's theology underpins and informs a developing spirituality, Kay demonstrates the need for prayer to be grounded in theology and for theology to be shaped by prayer."" --Ruth Gouldbourne, Minister, Bloomsbury Central Baptist Church, London ""As valuable as this work is for specialists, it is an even greater treasure for the faith and practice on the church. At the time when spirituality seems theologically dry, John Owen--through his remarkably insightful interpreter, Brian Kay--reminds us just how significant the doctrine of the Trinity is for our daily lives as Christians. I anticipate a wide readership for this impressive work."" --Michael Horton, J, Gresham Machen Professor of Systematic Theology and Apologetics, Westminster Seminary, CA ""This is a thoughtful and persistent attempt to explicate the connection between confessing a Trinitarian God and actually living as if it mattered. . . . The dichotomy between belief and behavior, so prevalent in modern religious life, is resolutely rejected by Kay. The resultant spirituality prescribed is honest, robust, orthodox, and above all genuinely Trinitarian. Kay has performed a great service for the church in our time. May he be widely read."" --Richard Lints, Professor of Theology, Gordon-Conwell Theological Seminary ""A great theme that leads us to the heart of the devotional theology of the ablest of Puritan thinkers. Kay's book opens, for the thoughtful explorer, a fresh path to a lost mine of spiritual treasure."" --Alan Spence, Minister in the United Reformed Church, London Brian K. Kay is Senior Pastor, Trinity Presbyterian Church, San Luis Obispo, CA.