Now the pastoral life of the Bronze Age was very active in the Dartmoor settlements; all antiquaries make much ado over this fact, yet they fail to see that the circulation of this farm life, the movement here and there of flocks and herds, required bridges, for the rivers then were not less wayward than they are now. Without bridges the farms would have stagnated. And another thing also needed the help of bridges: many domestic fires burnt a great deal of peat and wood, and wood had to be imported from neighbouring districts, probably in exchange for live stock. So, to visualise the farm life is to make it dependent on a ceaseless movement to and fro over very freakish rivers, which after rains and thaws were exceedingly turbulent and perilous. Deep gorges have been worn in the rocks through which the rivers flow; this alone is enough to prove that such wild rivers could not be forded by the tiny sheep and the small cattle of the Bronze Age. Even in mediæval times, as Thorold Rogers has proved, sheep were about as big as Mary’s little lamb; they were bred because their wool was the wealth--the Golden Fleece--that made England prosperous; and yet their cultivation failed to add to their national value by increasing their size. Sheep of the Bronze Age were probably smaller still; and how were they to cross the Dartmoor rivers unless bridges were built? Could sheep in those days swim like ducks, or did they float as naturally as logs? And since bridges must have been made here and there in order to keep the farming life from ruin, are we to suppose that the abundant granite blocks would not be used for piers and table stones? Are we to forget the instinctive delight in rude stonework shown everywhere by the dusky, short-statured race which for convenience we call Iberian?