Isaac Watts was a dissenting minister, theologian, philosopher, hymn writer and poet in the first half of the eighteenth century. Despite exercising significant influence over dissent and beyond he remains an understudied figure. In particular there has been little attempt to find coherent patterns of thought in his works. We examine Watts' view of the role of reason and the place of passion in the Christian life. These are shown to be foundational themes in his thought. In particular they lie behind his more practical works which attempted to bring reformation and revival to the church of his day. On reason Watts in many ways followed Enlightenment thought as expressed by John Locke. However he departed in significant ways which echo his Puritan background. As a result Watts is shown to be an 'Enlightenment Puritan' on this topic. On passion Watts accepted some of the view of the new sentimentalist thinkers but again continued significant elements of Puritan thought. Hence on both these areas Watts is shown to hold a modified Puritan position, modified that is in the light of the new thinking of his day. Watts' position on these foundational topics is then shown to lie behind his attempts to revive religion in the areas of preaching, praise and prayer. Watts' distinct views on these practical topics are shown to flow directly from his view of reason and passion. Hence in a time of increasing rationalism and sentimentality in the church Watts attempted to bring revival because of his modified Puritan views on reason and passion. As a result Watts' thought is shown to have a far greater degree of consistency than has been previously appreciated. It is not claimed that Watts has been relocated but that we have located him far more precisely.