Although this is emphatically a cargo vessel, these castles and fighting-top are there for the reasons already indicated by existing conditions at sea, and in this elaborate castellation with even small galleries aft we have the half-way house between the earlier and later Mediterranean merchantman: between the cargo-carrier of Rome and the carack, which was to develop into the galleon, thence into the East Indiaman, and eventually into the glorious clippers of the late nineteenth century. Thus this Pisan ship is for us most interesting, and she still links herself to primitive times by the use of one single square-sail and the old-fashioned method of steering by means of a rudder, not aft, but on the quarter. It is controlled by a tiller, but supported by tackles fore and aft, for it is now as heavy as a Thames sailing barge’s leeboards. Everything about this Pisan craft indicates that she was well and strongly built, and that expense was not spared. The elaborate work in her stern galleries, the influence of contemporary land architecture on her forecastle, the stout, thick rubbing strakes under which the ends of the beam come flush, the good strong rigging (three shrouds each side with tackles), the thick cable and the anchor secured to a shelf outside the hull on the starboard side—all these details show that the sculptor knew what he was depicting, and that the ship which he copied was a real sea-going vessel as used by genuine sailormen, and not the inaccurate muddled idea of an imaginative artist. The Pisans, the Venetians and Genoese were making plenty of money, and they could afford to send to sea a well-built, well-designed and well-found craft that would not cause the merchants to feel nervous about their valuable Eastern goods in the hold. With a mental picture before us of this slow, beamy, stout ship, built specially for seaworthiness and capacity to carry goods, rather than to excel in mobility, we can continue our study, and we shall be able to learn a great deal of the conditions prevailing in the mediæval Merchant Service if we examine the legal literature of the time. For obvious reasons, when there was so much coming and going and so much money at stake, maritime law began to assert itself from about the seventh century A.D. onwards, until, about six centuries later, we have practically every contingency catered for. Between the eighth and the thirteenth centuries there was very little alteration in the ships, the navigation and the manner of sea-trading. The big change comes in the thirteenth century, when the commercial renaissance begins, which, thanks to these vessels, made the great literary and artistic renaissance possible, gave to the world the new learning, the golden age of art, and left behind those wonderful achievements in stone. The merchant ship, therefore, is the basis of all in life that we respect and venerate.