[87] For this reason God, who never changes, altered the name of Abraham, since he was about to remain in a similar condition, in order that that which was to be firmly established might be confirmed by him who was standing firmly, and who was remaining in the same state in the same manner. But it was an angel who altered the name of Jacob, being the Word, the minister of God; in order that it might be confessed and ascertained, that there is none of the things whose existence is subsequent to that of the living God, which is the cause or unchangeable and unvarying firmness.... but of that harmony which, as in a musical instrument, contains the intensity and relaxation of sounds so as to produce an artistical combination of melody.