The most striking fact in the history of the pacing habit of action is its great antiquity. The average Englishman of to-day and the average American of twenty years ago have been united in insisting with the greatest vehemence that the pace is not a natural but an acquired gait, resulting from some injury or malformation. One of the great leaders on that side of the discussion called it “structural incongruity” arising from the breeding of the “thoroughbred” horse on the “slab-sided” mares of the West and South, and thought the idea was unanswerable, but never cited any instances to prove it. Now, the truth is, the earliest unquestioned evidence we have that horses paced is that furnished by the chisel of Phidias when he sculptured the horses on the frieze of the Parthenon at Athens, and that is two thousand three hundred and thirty-three years old. From the period when the sons of Japheth turned their attention to horse-breeding on the fruitful plains and valleys in the regions of the mountains of Ararat down to this culmination of Greek art, I have not been able to find any contemporaneous evidence of the existence of the lateral habit of action; but as we know it existed more than two thousand years ago, we are justified in concluding that among the original bands of horses, in their original habitat, pacers as well as trotters abounded. From the erection of the Parthenon in Athens, the occupation of Britain by the Romans, and through all the centuries down to the plantation of the colonies in this country, we have mountains of indisputable evidence of the antiquity of the pacer. In its place this topic will be quite fully discussed.