904. The spiritual have their own proper types of happiness that differ from those of the heavenly, as the gladness of the spiritual does from the joy of the heavenly. In order that spiritual types of gladness or happiness may be understood, an idea of them can be gotten from the harmonies of sounds, as well as from visual harmonies. Harmonies of sound, including speech, especially the meanings of speech, pertain to spiritual harmony, and the gladness resulting therefrom is spiritual gladness, due to which the music of the Church of old, and due to which singing in the heavens, is so delightful. Likewise, visual harmony, and the various forms of beauty therefrom, which touch the mind - and beauty in general, such as that of pleasure gardens and all things of that kind, or of buildings - these also pertain to spiritual gladness. More deeply, so does [the beauty] of understanding, hence the love of truth itself, or of truths, and consequently of enlightened knowledge. Spiritual gladnesses are the forms of heavenly qualities, which are - or if they are not, yet should be - their very essence.