I was curious myself to see what Leavis made a note
of.  I have a copy of Revaluation and here it is : 
(Leavis is commenting on 'Elegy to the Memory of an
Unfortunate lady')

'I remember to have heard, incredulously, a theory,
purporting to come from a critic of high repute, that
is worth mentioning becausue it calls attention to
certain essential characteristics of the poem.  The
theory was that Pope opened in all solemnity, but
finding it impossible to continue in so high-flown a
strain without smiling at himself (he had, after all,
a sense of humour), slipped in a qualifying element of
burlesque and achieved a subtle total effect to that
of Prufrock. The evidence?  Well, for example this : 

As into air the purer spirits flow,
And sep'rate from teheir kindred dregs below;
So flew the soul to its congenial place, 
Nor left one virtue to redeem her Race. '

- vishvesh

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