Flogging a dead horse is a commonly used idiom here in the UK. If someone is trying to convince someone else to do or feel something without any hope of succeeding, we say they're flogging a dead horse. This is used when someone is trying to raise interest in an issue that no-one supports anymore; beating a dead horse will not make it do any more work. 1. Similarly, the tribal wisdom of the Dakota Indians, passed on from generation to generation, says that, "When you discover...