'A watchtower,' as in Isaiah 23:13, signifies the delusions, or fantasies, that come from a love of self, even a worship of oneself. It can become a worship of self when a person sets himself up above everybody else, with pride and arrogance.

(References: Arcana Coelestia 1306)

'To cover under wings,' as in Psalms 91:4, signifies guarding with the divine truth, which is the divine spiritual. 'Wings' signify spiritual truths. 'Wings,' when related to the Lord, signify the divine spiritual. In the opposite sense, 'wings' relate to falsities and rationalizations from them.

(References: Apocalypse Revealed 245; Deuteronomy 32:10-12; Divine Providence 20-25; Ezekiel 16:8; Malachi 4:2; Matthew 23:37; Psalms 17:8, 26:8, 57:2, 63:8)