the greased pig

In Margaret Atwood's lecture "Spotty Handed Villainesses " she says that the writing process is "like wrestling a greased pig in the dark"
what exactly is she referring to re. the greased pig?

Margaret Atwood grew up at least partly in rural environments (northern Ontario, Quebec), in which she may have become acquainted with such rural pastimes as trying to catch a greased pig, a popular event at church picnics, firemen's picnics, and suchlike civic celebrations. To catch a greased pig you naturally had not only to catch up with it, but also wrestle it to submission. Just to make it harder she imagines doing it in the dark. The obvious problem is that a greased pig is very slippery and hard to hang on to.
SS