The evidentiary rule Neville applies to his own testimony, drawn from the Mosaic requirement of two witnesses. When you bring two you have conclusive evidence if they agree, because two by nature would be opposition, enmity, difference - so when two different persons agree in testimony it is conclusive. His own two are named: he had the experience, and then searching the ancient scripture he found the supporting text for it, so there is agreement in testimony and therefore it is conclusive. He says he presented both in the last chapter of The Law and the Promise - the story as it happened to him, and the scripture that supports it. The same pair appears elsewhere as the inward testimony of the Spirit and the outward testimony of scripture. It matters because it is the only formal argument he offers for believing him at all: not authority, not consistency, but the independence of the two accounts. About twenty-four lectures.