ts
of the House of Aviz_ in his _Sons of Don John I._

The maps and illustrations have been planned in a regular series.

I. As to the former, they are meant to show in an historical succession
the course of geographical advance in Christendom down to the death of
Prince Henry (1460). Setting aside the Ptolemy, which represents the
knowledge of the world at its height in the pre-Christian civilisation,
and the Edrisi which represents the Arabic followers of Ptolemy, whose
influence upon early Christian geography was very marked, all the maps
reproduced belong to the science of the Christian ages and countries.
The two Mappe-mondes above referred to are both placed in the
introductory chapter, and are treated only as the most important
examples of the science which the Graeco-Roman Empire bequeathed to
Christendom, but which between the seventh and thirteenth centuries was
chiefly worked upon by the Arabs. Among early Christian maps, that of
St. Sever, possibly of the eighth century, the Anglo-Saxon map of the
tenth century, the Turin Map of the eleventh, and the Spanish map of the
twelfth (1109), represent very crude and simple types of sketches of the
world, in which within a square or oblong surrounded by the ocean a few
prominent features only, such as the main divisions of countries, are
attempted. The Anglo-Saxon example, though greatly superior to the
others given here, essentially belongs to this kind of work, where some
little truth is preserved by a happy ignorance of the travellers' tales
that came into fashion later, but where there is only the vaguest and
most general knowledge of geographical facts.

On the other hand, in the next group, to which the Psalter map is
allied, and in which the Hereford map is our best example, mythical
learning--drawn from books like Pliny, Solinus, St. Isidore, and
Martianus Capella, which collected stories of beasts and monsters,
stones and men, divine, human, and natural marvels on the principle
_Credo quia impossible_--has overpowered every other consideration, and
a map of the world becomes a great picture-book of curious objects, in
which the very central and primary interest of geography is lost. But by
the side of and almost at the same time as these specimens of
geographical mythology, geographical science had taken a new start in
the coast charts or portolani of Balearic and Italian seamen, some
specimens of which form our next set of maps.

Dulcert's portolano of