23. _Space to spire._ From the wide opening between the colonnades to the cross on the top of the lantern surmounting the dome.
34. _Protoplast._ Used apparently for protoplasm, a substance constituting the physical basis of life in all plants and animals.
39. Into his musical palace came the wonderful Dead in a glorified form, and also Presences fresh from the Protoplast, while, for the moment, he himself in the ardor of musical creation felt himself raised to the level of these exalted ones.
53. _Consider it well._ On the mystery of musical creation and on its permanence see Cardinal Newman's sermon on "The Theory of Development in Christian Doctrine." (Quoted in part, in Berdoe's _Browning Cyclopædia_.)
57. _Palace of music._ Cf. the description of the glowing banquet-room in Keats's "Lamia":
"A haunting music, sole perhaps and lone Supportress of the faery-roof, made moan Throughout, as fearful the whole charm might perish."
The damsel with the dulcimer in Coleridge's "Kubla Khan" sings of Mount Abora, and the poet says:
"Could I revive within me Her sympathy and song To such a deep delight 'twould win me That with music loud and long I would build that dome in air, That sunny dome, those caves of ice! And all who heard should see them there."
In Tennyson's "Gareth and Lynette" (l. 270), Merlin says to Gareth in describing Camelot,
"For and ye heard a music, like enow They are building still, seeing the city is built To music, therefore never built at all, And therefore built forever."
There are also more ancient accounts of this union of music and architecture. Amphion, King of Thebes, played on his lyre till the stones moved of their own accord into the wall he was building. When King Laomedan built the walls of Troy, Apollo's lyre did similar service to that of Amphion in Thebes. For an interesting account of "Voice Figures" see _The Century Magazine_, May 1891.
64. _What was, shall be._ For this faith in the actual permanence of what seemed so evanescent, compare Adelaide Procter's "Lost Chord."
69. _There shall never be one lost good._ Whatever of good has existed must always exist. Evil, being self-destructive, finally "is null, is naught." This is the Hegelian doctrine. Walt Whitman said on reading Hegel, "Roaming in thought over the Universe I saw the little that is Good steadily hastening towards immortality. And the vast all that is called Evil I saw hastening to merge itself and become lost and dead." (Berdoe, _Browning Cyclopædia_, page 40.)