Alexander Pope's 'An Essay on Criticism', lines 337–349:
But most by Numbers judge a Poet's Song,
And smooth or rough, with them, is right or wrong;
In the bright Muse tho' thousand Charms conspire,
Her Voice is all these tuneful Fools admire,
Who haunt Parnassus but to please their Ear,
Not mend their Minds; as some to Church repair,
Not for the Doctrine, but the Musick there.
These Equal Syllables alone require,
Tho' oft the Ear the open Vowels tire,
While Expletives their feeble Aid do join,
And ten low Words oft creep in one dull Line,
While they ring round the same unvary'd Chimes,
With sure Returns of still expected Rhymes.
I don't understand the line in bold. Can you help me?