<P> While Amerigo Vespucci is usually credited for coming up with the term "New World" (Mundus Novus) for the Americas in his 1503 letter, certainly giving it its popular cachet, similar terms had nonetheless been used and applied before him . </P> <P> The Venetian explorer Alvise Cadamosto had used the term "un altro mundo" ("another world") to refer to sub-Saharan Africa, which he explored in 1455 and 1456 on behalf of the Portuguese . However, this was merely a literary flourish, not a suggestion of a new "fourth" part of the world . Cadamosto was quite aware sub-Saharan Africa was firmly part of the African continent . </P> <P> The Italian - born Spanish chronicler Peter Martyr d'Anghiera often shares credit with Vespucci for designating the Americas as a new world . Peter Martyr used the term Orbe Novo (literally, "New Globe", but often translated as "New World") in the title of his history of the discovery of the Americas as a whole, which began to appear in 1511 (cosmologically, "orbis" as used here refers to the whole hemisphere, while "mundus" refers to the land within it). Peter Martyr had been writing and circulating private letters commenting on Columbus's discoveries since 1493 and, from the start, doubted Columbus's claims to have reached East Asia ("the Indies"), and consequently came up with alternative names to refer to them . Only a few weeks after Columbus's return from his first voyage, Peter Martyr wrote letters referring to Columbus's discovered lands as the "western antipodes" ("antipodibus occiduis", letter of May 14, 1493), the "new hemisphere of the earth" ("novo terrarum hemisphaerio", September 13, 1493), and in a letter dated November 1, 1493, refers to Columbus as the "discoverer of the new globe" ("Colonus ille novi orbis repertor"). A year later (October 20, 1494), Peter Martyr again refers to the marvels of the New Globe ("Novo Orbe") and the "Western hemisphere ." ("ab occidente hemisphero"). </P> <P> Christopher Columbus touched the continent of South America in his 1498 third voyage . In his own 1499 letter to the Catholic Monarchs of Spain, reporting the results of his third voyage, Columbus relates how the massive waters of the Orinoco delta rushing into the Gulf of Paria implied that a previously unknown continent must lie behind it . However, bowing to the classical tripartite division of the world, Columbus discards that hypothesis and proposes instead that the South American landmass is not a "fourth" continent, but rather the terrestrial paradise of Biblical tradition, not a previously unknown "new" part of the world, but a land already "known" (but location undiscovered) by Christendom . In another letter (to the nurse of Prince John, written 1500), Columbus refers to having reached a "new heavens and world" ("nuevo cielo e mundo") and that he had placed "another world" ("otro mundo") under the dominion of the Kings of Spain . </P>

1. what were the three main reasons for european exploration of the new world