missionaries
both to India and to China, and a bishop was appointed for the latter
field. Ibn Wahab, who traveled to China in the ninth century, found images
of Christ and the apostles in the Emperor's court.[407] Such a learned body
of men, knowing intimately the countries in which they labored, could
hardly have failed to make strange customs known as they returned to their
home stations. Then, too, in Alfred's time (849-901) emissaries went {104}
from England as far as India,[408] and generally in the Middle Ages
groceries came to Europe from Asia as now they come from the colonies and
from America. Syria, Asia Minor, and Cyprus furnished sugar and wool, and
India yielded her perfumes and spices, while rich tapestries for the courts
and the wealthy burghers came from Persia and from China.[409] Even in the
time of Justinian (c. 550) there seems to have been a silk trade with
China, which country in turn carried on commerce with Ceylon,[410] and
reached out to Turkestan where other merchants transmitted the Eastern
products westward. In the seventh century there was a well-defined commerce
between Persia and India, as well as between Persia and
Constantinople.[411] The Byzantine _commerciarii_ were stationed at the
outposts not merely as customs officers but as government purchasing
agents.[412]

Occasionally there went along these routes of trade men of real learning,
and such would surely have carried the knowledge of many customs back and
forth. Thus at a period when the numerals are known to have been partly
understood in Italy, at the opening of the eleventh century, one
Constantine, an African, traveled from Italy through a great part of Africa
and Asia, even on to India, for the purpose of learning the sciences of the
Orient. He spent thirty-nine years in travel, having been hospitably
received in Babylon, and upon his return he was welcomed with great honor
at Salerno.[413]

A very interesting illustration of this intercourse also appears in the
tenth century, when the son of Otto I {105} (936-973) married a princess
from Constantinople. This monarch was in touch with the Moors of Spain and
invited to his court numerous scholars from abroad,[414] and his
intercourse with the East as well as the West must have brought together
much of the learning of each.

Another powerful means for the circulation of mysticism and philosophy, and
more or less of culture, took its start just before the conversion of
Constan