and at length found myself, as the shades of the evening drew on, within view of the melancholy House of Usher. I know not how it was-but, with the first glimpse of the building, a sense of insufferable gloom pervaded my spirit. - Poe, "The Fall of the House of Usher" In the bolded section, what is the benefit of using "I know not ..." instead of "I don't know" or another more concise syntax? It emphasizes the means of travel. It establishes an earlier time period. It puts more emphasis on the positive. It suggests an uneducated narrator.

It establishes an earlier time period.

Explanation:

In Edgar Allen Poe's short story "The Fall of The House of Usher" tells the story of how the Usher family literally and figuratively crumble to the grown. This story have themes of madness, isolation and even some gothic, eerie horror sense to it.

The given lines are from the initial parts of the story where the narrator was approaching the Usher House where he was to stay with his friend Roderick usher and his sister Madeline. In his description of his walk up to the house, he used the word "I know not". This is an often used word that is significant especially of the earlier periods of time in English writing where the form of English used is more of the different form than the simpler ones we are accustomed to nowadays. The form of syntax in the use of this phrase instead of the much more easily understandable "I don't know" is suggestive of how the time difference, the period difference is during the time the story was written or based of.