In the Highlands of Scotland sheep often wander off into places they can’t get out off. They jump down onto ledges 10 or 12 feet below to enjoy the grass which is lush and sweet. However, down on the ledges they can’t get up easily, especially when they have a belly full of grass! They may be there for days until they have eaten all the grass.
The shepherd hears them bleating in distress but the shepherd does not go and get them immediately. Shepherds have learned that if they go down there when the sheep first strays, the sheep will often be so foolish and skittery that they will jump right over the precipice and be killed.
The shepherds wait until the sheep are so weak that that cannot stand. Then they will go down, put a rope around them and pull the sheep to safety.
Source: From one of Gordon Macdonald's fine books.