Sceachanna iarann.

Before the Normen came the Irish were happy enough pastoralists, roaming. Banks and ditches did, sceachs or thorny bushes were thrun into gaps. Then the upright ones came; the Normen, then the English down south and the Scots up north. They were driven mad by the sceach-in-the-gap mentality. They liked gates, fixed to upright things, as they themselves were upright. Eventually the Irish started using gates too, but refused to fix them to upright things. Gate-posts reminded us of the upright mythersome ones. Effectively, gates replaced sceachs, and were just fucked into gaps.
This is in no way a summary Chapter 5 of this marvellous book, which seems to be out of print, which makes me glad I freed a copy from a dusty room a while back.