But when the lady passed, there came
A tongue of light, a fit of flame;
And Christabel saw the lady's eye,
And nothing else saw she thereby,
Save the boss of the shield of Sir Leoline tall,
Which hung in a murky old niche in the wall.
O softly tread, said Christabel,
My father seldom sleepeth well."

When, after the hurrying anapaests, the verse returns to the strict
iambic measure in the last couplet, the effect is a hush, in harmony with
the meaning of the words.[21]

"Christabel" is not so unique and perfect a thing as "The Ancient
Mariner," but it has the same haunting charm, and displays the same
subtle art in the use of the supernatural. Coleridge protested that it
"pretended to be nothing more than a common fairy tale." [22] But Lowell
asserts that it is "tantalising in the suggestion of deeper meanings than
were ever there." There is, in truth, a hint of allegory, like that
which baffles and fascinates in Christina Rossetti's "Goblin Market"; a
hint so elusive that the comparison often made between Geraldine and
Spenser's Duessa, is distressing to a reader of sensitive nerves. That
mystery which is a favourite weapon in the romanticist armoury is used
again here with consummate skill. What was it that Christabel saw on the
lady's bosom? We are left to conjecture. It was "a sight to dream of,
not to tell," [23] and the poet keeps his secret. Lamb, whose taste was
very fine in these matters, advised Coleridge never to finish the poem.
Brandl thinks that the idea was taken from the curtained picture in the
"Mysteries of Udolpho"; and he also considers that the general
situation--the castle, the forest, the old father and his young daughter,