37. The letter [of the unity] is common, but the Substance of God and the substance of man are different. We shall be, the Father and the Son [already] are, one; we shall be one by grace, the Son is so by substance. Again, unity by conjunction is one thing, unity by nature another. Finally, observe what it is that Scripture hath already recorded: “That they may all be one, as Thou, Father, art in Me, and I in Thee.” S. John xvii. 21.