Prince Henry's active share in the work of exploration is usually dated only from the Conquest of Ceuta. Here we are told in one of our earliest authorities (Diego Gomez) he gained information, from Moorish prisoners, merchants, and other acquaintance "of the passage of traders from the coasts of Tunis to Timbuktu and to Cantor on the Gambia, which led him to seek those lands by the way of the sea;" and, to come to details, he was among other things, "told of certain tall palms growing at the mouth of the Senegal [or Western Nile], by which he was able to guide the caravels he sent out to find that river." It will be important hereafter to examine the evidence which had been accumulated for such belief up to the fifteenth century: now it will be enough to say: 1. That Prince Henry was probably of the same opinion as the ordinary cartographer of his time about the peninsular shape of Africa. 2. That the "shape" in question was usually satisfied with what we should now call the Northern half of the Continent, making the Southern coast of "Guinea" continue directly to the Eastern, Abyssinian, or Indian Ocean. 3. That trade had now (c. 1415) been long maintained between this "Guinea coast" and the Mediterranean seaboard--chiefly by Moorish caravans across the Sahara. 4. That something, though little, was known in Western Christendom about the Christian faith and king of Abyssinia; for "Prester John's" story in the fifteenth century had really become a blend of rumours from Central (Nestorian) Asia and Eastern (Abyssinian) Africa. In Prince Henry's work we may distinguish three main objects--scientific, patriotic, and religious. First of all he was a discoverer, for the sake of the new knowledge then beginning. He was interested in the exploration of the world in general, and of the sea-route round Africa to India in particular. Dinis Diaz, returning from his discovery of Cape Verde (Az., ch. xxxi.), brought home a "booty not so great as had arrived in the past," but "the Infant thought it very great indeed, since it came from that land", and he proportioned his rewards to exploration rather than to trade profits. Nuno Tristam in 1441 (Az., ch. xiii.) reminds Antam Gonçalvez that "for 15 years" the Infant has "striven ... to arrive at ... certainty as to the people of this land, under what law or lordship they do live." Azurara, though always more prone to emphasize the emotional than the scientific, himself assigns as the first reason for the Infant's discoveries, his "wish to know the land that lay beyond the isles of Canary and that cape called Bojador, for that up to his time, neither by writings nor by the memory of man, was known with any certainty the nature of the land" (Az., ch. vii.).