Auden visited Ischia, an island in the Gulf of Naples, with Chester Kallman, in spring and summer 1948, and spent about six weeks on Ischia; In Praise of Limestone was the first poem he wrote in Italy. The titular limestone is characteristic of the Mediterranean landscape and is considered an allegory of history in the poem; the properties of this sedimentary rock invoke the sedentary and domestic picture of Mediterranean culture. The calcium in limestone makes it water-soluble and easily eroded, yet limestone builds up over eons, a stratum at a time, out of organic matter, recalling the stratified history of Mediterranean civilisation. Interpreting the metaphor of ground in poetry, the critic Rainer Emig writes, The ground [is] a perfect symbol of cultural, ethnic, and national identity, a significatory confluence of the historical and the mythical, individual and collective.