This is a quote from the book "Animal Farm" by George Orwell
... would be a hard one.

The windmill presented unexpected difficulties. There was a good quarry of limestone on the farm, and plenty of sand and cement had been found in one of the outhouses, so that all the materials for building were at hand. But the problem the animals could not at first solve was how to break up the stone into pieces of suitable size. There seemed no way of doing this except with picks and crowbar...

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