An unusual image, of possibility swarming like larvae, ready to burst into butterfly winged realization.  

… to swarm with larval possibility. 

For a rich selection of other Heaney similes and metaphors, see our celebration of Beowulf, both his version and that of Kevin Crossley-Holland.

Source: Seamus Heaney, Finders Keepers: Selected prose 1971-2001 (London: Faber and Faber, 2003), p. 245

Photo credit: GLady at pixabay