And he farther acquaints us with the reason why the Turks choose these Arabian Horses when young, because, if continued long in the hands of the Arabs, they are small, stunted, and deformed in shape; whereas, when brought into Turkey, a land of greater plenty than the deserts of Arabia, they acquire a greater perfection both of size and shape. Now, whether these Turks and Arabs are of the same or different extraction, may perhaps be very little to our purpose; but it is absurd to suppose that providence has bestowed a virtue on a part only of this species produced in any one country, (which species was undoubtedly designed for the use of man) and that mankind should not be able, in any age, to determine with precision this virtue, or fix any criterion, whereby to judge with any certainty. Seeing then, this is the case, how shall we account for the various perfection and imperfection in the breed of these foreign Horses; for we perceive it not determined to those of Turkey, Barbary, or Arabia, but from each of these countries some good, some bad Stallions are sent us? What shall we do? Shall we continue to impute it to the good old phrase of blood, the particular virtue of which, no man ever yet could ascertain, in any one particular instance, since Horses were first created? or shall we say that nature has given these foreign Horses a finer texture, a finer attitude, and more power than any other Horses we know of; and that these very Horses, and their descendants always did, and always will surpass each other in speed and bottom, according to their different degrees of power, shape, elegance, and proportion? But there is also a certain length determined to some particular parts of this animal, absolutely necessary to velocity, of the particularity and propriety of which length, all jockeys appear to be intirely** ignorant, from the latitude of their expression, which is that a racer must have length somewhere. If I might now be allowed to give my opinion of this propriety of length, I should say it consisted in the depth and declivity of the shoulders, and in the length of the quarters and thighs, and the insertion of the muscles thereof. The effect of the different position or attitude of the shoulders in all Horses, is very demonstrable: if we consider the motion of a shoulder, we shall find it limited to a certain degree by the ligamentous and the tendinous parts, which confine it to its proper sphere of acting; so that if the shoulder stand upright, the Horse will not be able to put his toes far before him, but will acquire only such a particular degree of space at each step or movement; but if the shoulders have a declivity in them, he cannot only put his toes farther before him, but a greater purchase of ground will be obtained at every stroke.