Walter Savage Landor's hard perfection

Ah what avails the sceptred race,
    Ah what the form divine!
What every virtue, every grace!
    Rose Aylmer, all were thine.
Rose Aylmer, whom these wakeful eyes
    May weep, but never see,
A night of memories and of sighs
    I consecrate to thee.

Rose Aylmer is a famous little poem by a great poet of the narrowest possible accomplishment and the best possible middle name. The top google search for the poem contains an error - "A night of memories and sighs" (842 hits) instead of "A night of memories and of sighs" (102 hits). When I saw Joan Didion misquote the line in the same way here, my ears pricked up, because I remembered the main character in Vikram Seth's _A Suitable Boy_ making the same mistake in a graveyard on a date with a poet, who unhelpfully notes the essential extra "of" without saying why it matters. The line is easier to say (and recall) as pure iambic tetrameter, like the rest of the poem, but as written the nouns (esp. the latter two) are emphasized; the sudden heavy emotional weight causes the rhythm to stumble; the reader is forced to pause and consider the relationship between the latter two nouns and then back to "night" - just "a" night. It's a small and subtle point, but as good an example as any I can think of of the difficulty and rewards of reading poetry.