Some, indeed, might be thought to reach islands by swimming, in case these were very near; but some islands are so remote from continental lands that it does not seem possible that any creature could reach them by swimming.

It is not an incredible thing, either, that some animals may have been captured by men and taken with them to those lands which they intended to inhabit, in order that they might have the pleasure of hunting; and it can not be denied that the transfer may have been accomplished through the agency of angels, commanded or allowed to perform this labour by God." But this difficulty had now assumed a magnitude of which St.Augustine never dreamed.

Most powerful of all agencies to increase it were the voyages of Columbus, Vasco da Gama, Magellan, Amerigo Vespucci, and other navigators of the period of discovery.

Still more serious did it become as the great islands of the southern seas were explored.

Every navigator brought home tidings of new species of animals and of races of men living in parts of the world where the theologians, relying on the statement of St.Paul that the gospel had gone into all lands, had for ages declared there could be none; until finally it overtaxed even the theological imagination to conceive of angels, in obedience to the divine command, distributing the various animals over the earth, dropping the megatherium in South America, the archeopteryx in Europe, the ornithorhynchus in Australia, and the opossum in North America.
The first striking evidence of this new difficulty was shown by the eminent Jesuit missionary, Joseph Acosta.