419. As celestial things are the holy things of love and the derivative goods, so spiritual things are the truths and goods of faith; for it belongs to faith to understand not only what is true, but also what is good. The knowledges of faith involve both. But to be such as faith teaches is celestial. As faith involves both of these, they are signified by two instruments, the harp and the organ. The harp, as everyone knows, is a stringed instrument, and therefore signifies spiritual truth; but the organ, being intermediate between a stringed instrument and a wind instrument, signifies spiritual good.