“I will sing a new song to you, O God” (Ps 142[143]: 9). The new song is a song of grace; the new song is the song of one made new; the new song is the song of the New Covenant. “I will sing,” he says, “a new song to you.” But lest you think that grace leaves the Law behind, when in fact the Law is fulfilled by grace, he says, “On the ten-stringed psaltery I will sing a psalm to you.” The “ten-stringed psaltery” means the Law’s ten commandments: there will I sing a psalm to you; there will I rejoice in you; there will I sing you a new song, because love is the fulfilling of the Law. People who don’t have love may be able to carry the psaltery, but they can’t sing on it.  (EnPs 142[143], 16; PL 37, 1866)