God is but one, yet are there three distinct persons subsisting in one Godhead. This is a sacred mystery, which the light within man could never have discovered. As the two natures in Christ, yet but one person, is a wonder; so three persons, yet but one Godhead. Here is a great deep, the Father God, the Son God, the Holy Ghost God; yet not three Gods, but one God. The three persons in the blessed Trinity are distinguished, but not divided; three substances, but one essence. This is a divine riddle, where one makes three, and three make one. Our narrow thoughts can no more comprehend the Trinity in Unity, than a nut-shell will hold all the water in the sea.
- Thomas Watson (c. 1620-1686)