In brightness rushing and on either side
Were banks that with spring's wondrous hues might vie
And from that river living sparks did soar
And sank on all sides in the flow'rets bloom
Like precious rubies set in golden ore
Then as if drunk with all the rich perfume
Back to the wondrous torrent did they roll
And as one sank another filled its room."

Commenting on this passage, Von Humboldt says "It would seem as if this
picture had its origin in the poet's recollection of that peculiar and
rare phosphorescent condition of the ocean in which luminous points
appear to rise from the breaking waves and, spreading themselves over
the surface of the waters, convert the liquid plain into a moving sea of
stars." This mention of a sea brings to mind the striking fact that Dean
Church has pointed out, viz., when Dante speaks of the Mediterranean, he
speaks not as a historian or an observer of its storms or its smiles but
as a geologist. The Mediterranean is to him: "The greatest _valley_
in which water stretcheth." (Par. IX, 82.)

So also when he speaks of light he regards it not merely in its
beautiful appearances but in its natural laws (Purg. XV). And when Dante
comes to describe the exact color, say of an apple blossom, his splendid
and unequalled power as a scientific observer of Nature and a poet is
most evident. Ruskin (Mod. Painters III, 226) commenting on the passage:
flowers of a color "less than that of roses but more than that of
violets" (Purg. XXXII, 58) makes this interesting remark: "It certainly
would not be possible in words, to come nearer to the _definition_
of the exact hue which Dante meant--that of the apple blossom. Had he
employed any simpler color phrase, as 'pale pink' or 'violet pink' or