There are several possible sources for the line referring to squeezing "the universe into a ball."

The usual critical interpretation is that Eliot is alluding to Andrew Marvell's "To His Coy Mistress" (first published in 1681) but, as Carol Barton suggested in a letter to this editor, he might also be gleaning the line from his own "Prufrock's Pervigilium," a 38 line insertion in the original notebook of "The Love Song" that Eliot mostly deleted.