osion, and Columbus himself, seeing this danger, flung
himself into the sea, seized a floating oar, and thus gained the shore.
He was not far from Lisbon, and from this time made Lisbon his home for
many years.(*)

(*) The critics challenge these dates, but there seems to be
good foundation for the story.

It seems clear that, from the time when he arrived in Lisbon, for
more than twenty years, he was at work trying to interest people in his
"great design," of western discovery. He says himself, "I was constantly
corresponding with learned men, some ecclesiastics and some laymen,
some Latin and some Greek, some Jews and some Moors." The astronomer
Toscanelli was one of these correspondents.

We must not suppose that the idea of the roundness of the earth was
invented by Columbus. Although there were other theories about its
shape, many intelligent men well understood that the earth was a globe,
and that the Indies, though they were always reached from Europe by
going to the East, must be on the west of Europe also. There is a
very funny story in the travels of Mandeville, in which a traveler is
represented as having gone, mostly on foot, through all the countries
of Asia, but finally determines to return to Norway, his home. In his
farthest eastern investigation, he hears some people calling their
cattle by a peculiar cry, which he had never heard before. After he
returned home, it was necessary for him to take a day's journey westward
to look after some cattle he had lost. Finding these cattle, he also
heard the same cry of people calling cattle, which he had heard in the
extreme East, and now learned, for the first time, that he had gone
round the world on foot, to turn and come back by the same route, when
he was only a day's journey from home, Columbus was acquainted with such
stories as this, and also had the astronomical knowledge which almost
made him know that the world was round, "and, like a ball, goes spinning
in the air." The difficulty was to persuade other people that, because
of this roundness, it would be possible to attain Asia by sailing to the
West.

Now all the geographers of repute supposed that there was not nearly
so large a distance as there proved to be, in truth, between Europe and
Asia. Thus, in the geography of Ptolemy, which was the standard book
at that time, one hundred and thirty-five degrees, a little more than
one-third of the earth's circumference, is given to the space b