<P> Pomponius Mela, the first Roman geographer, asserted that the earth had two habitable zones, a North and South one, but that it would be impossible to get into contact with each other because of the unbearable heat at the Equator . </P> <P> From the time of St Augustine, the Christian church was skeptical of the notion . Augustine asserted that "it is too absurd to say that some men might have set sail from this side and, traversing the immense expanse of ocean, have propagated there a race of human beings descended from that one first man ." </P> <P> In the Early Middle Ages, Isidore of Seville's widely read encyclopedia presented the term "antipodes" as referring to antichthones (people who lived on the opposite side of the Earth), as well as to a geographical place; these people came to play a role in medieval discussions about the shape of the Earth . In 748, in reply to a letter from Saint Boniface, Pope Zachary declared the belief "that beneath the earth there was another world and other men, another sun and moon" to be heretical . In his letter, Boniface had apparently maintained that Vergilius of Salzburg held such a belief . </P> <P> The antipodes being an attribute of a spherical Earth, some ancient authors used their perceived absurdity as an argument for a flat Earth . However, knowledge of the spherical Earth was widespread during the Middle Ages, only occasionally disputed--the medieval dispute surrounding the antipodes mainly concerned the question whether people could live on the opposite side of the earth: since the torrid clime was considered impassable, it would have been impossible to evangelize them . This posed the problem that Christ told the apostles to evangelize all mankind; with regard to the unreachable antipodes, this would have been impossible . Christ would either have appeared a second time, in the antipodes, or left the damned irredeemable . Such an argument was forwarded by the Spanish theologian Alonso Tostado as late as the 15th century and "St. Augustine doubts" was a response to Columbus's proposal to sail westwards to the Indies . </P>

What is directly opposite me on the earth