The longest sentence in English poetry—143 words and, if a compound is counted as two, 144—is in Book IV, Conto III, P.426.
We must understand, of course, that true sentence-length does not really depend on putting a full-stop as late as possible and substituting commas and semi-colons and colons for it wherever we can. The true length is organic. The construction is such that the components, however independent-seeming, are grammatically inseparable. Many of them are really subordinate clauses or else contain words that internally link them together, as against mere external linkage by means of which add mechanically rather than organically to the length of a sentence. In the instance from we have an ultra-Homeric simile, a long-drawn-out comparison whose sense, beginning with "As", is completed only when the full comparative picture has been painted and then the central situation which the simile illuminates is stated. If a sentence starts with an "As", it cannot be complete until there is a "so also" or its equivalent in some form at the other end to introduce the main theme.
Further, in a truly long sentence, not only is the syntax organic: the very organicity has what we may call a living limita-tiveness which practically ensures that the sentence would assimilate within its vital system only the right amount of detail necessary to unfold the central meaning: a limit is intrinsically imposed upon the length, rendering this length, and no other, vitally significant. Such organicity is different from that of a passage where to enrich the theme one can go on drawing the length out with illustrative
Thus by Anne, Countess of Winchelsea (1660?-1720), cast in heroic couplets, consists of one long sentence running into 50 lines and 367 words or, with each of its four compounds rating as two words, 371. The main clause does not appear until the forty-sixth line; most of the poem up to this point is a series of qualifying clauses. But the structure has no living limitativeness in the stria sense. The poem starts with
In such a night, when every louder wind
Is to its distant cavern safe confined—
and continues with particular on particular of imagery intended to create an atmosphere of peace, all the images introduced by the conjunction "when." The images do serve a single mood or impression, but they are not dictated by any palpable necessity which would exclude others—nor are they even in direct spatial relationship among themselves. There is no internal reason why, with more abundant observation, the poet should not have gone on adding many more than she had already done. In the sentence from Sri Aurobindo we have no open-endedness of this sort. The theme demands a special restricted development: nothing except a number of relevant details can be brought in within the organic form, giving it its length.
Sri Aurobindo's theme is: how, on hearing some words from her father Aswapathy, Savitri wakes up to the sense of her true mission:
As when the mantra sinks in Yoga's ear,
Its message enters stirring the blind brain
And keeps in the dim ignorant cells its sound;
The hearer understands a form of words
And, musing on the index thought it holds,
He strives to read it with the labouring mind,
But finds bright hints, not the embodied truth:
Then, falling silent in himself to know
He meets the deeper listening of his soul:
The Word repeats itself in rhythmic strains:
Thought, vision, feeling, sense, the body's self
Are seized unalterably and he endures
An ecstasy and an immortal change;
He feels a Wideness and becomes a Power,
All knowledge rushes on him like a sea:
Transmuted by the white spiritual ray
He walks in naked heavens of joy and calm,
Sees the God-face and hears transcendent speech:
An equal greatness in her life was sown.
- K.D. Sethna
(Sri Aurobindo - The Poet, pp. 391-393)