In the ancient and Jewish churches, 'songs' were prophesies about the Lord, especially His coming in the world, subjugation of evil spirits, and liberation of the faithful from their assaults. 'Heavenly songs' are voiced affections or affections expressed and modified by sounds. As thoughts are expressed by conversation, so affections are expressed by songs. From the balance and flow of the variations, angels perceive the object of the affection.

(Reference: Conjugial Love 55)

1304. That 'let us build ourselves a city and a tower' means that they fabricated a form of doctrine and of worship becomes clear from the meaning of 'a city' and from the meaning of 'a tower', dealt with in the paragraphs that follow this. The Church is such that when charity towards the neighbour departs and self-love takes its place, the doctrine of faith is of no account at all except insofar as it can be converted into worship of self. Nor do people consider that worship contains anything holy unless it exists for the sake of self, thus unless it is worship of self. This applies to all self-love. In fact a person who loves himself more than others not only hates everybody who is not subservient to him and shows no favour to them except when they have become subservient, but also, to the extent that he is not prevented, he plunges even into exalting himself above God. The fact that self-love is such when given free rein I have been shown in actual occurrences. These are the things meant by 'a city and a tower'. Self-love, and every desire springing from it, is of all things the filthiest and most unholy, and is very hell itself. From this anyone may deduce the nature of the worship that has such as this within it.