6 EARLY MEDIEVAL SPAINnotable for their uncompromising and even violent hostility to pa-
ganism and to heresy, but whether this indicates a complete triumph
or a hard struggle in the peninsula is unclear.
Spanish bishops had begun by then to play an important role in
the internal disputes of the Church. In the fourth century Arian
controversy over the equality and coeternity of the Father and the
Son in the Trinity, Potamius of Lisbon and Gregory of Elvira were
amongst the principal Western proponents and opponents of the
heretical doctrine. Bishop Hosius of Cordoba was one of the leading
ecclesiastical advisers of the emperor Constantine (306-337) and is
also suspected of influencing the emperor in favour of Arius's teach-
ings. In addition Spain produced a heresiarch of her own in the
person of Priscillian, Bishop of Avila, who was executed by a fellow
Spaniard, the emperor Magnus Maximus, in 385, in the first use of
secular punishment for a purely ecclesiastical offenceY
While the impression of Roman Spain is one of unity, and indeed
in terms .of architecture, engineering, art and religion, almost of
uniformity with the rest of the Empire, it is essential to appreciate
how fragile this was. It was an artificial imposition that negated much
of the geography and past history of the peninsula. A full apprecia-
tion of the civilisation of Spain, not only in Antiquity and the Middle
Ages but for every stage of its history up to the present, is dependent
upon some understanding of its geography.
Despite being a peninsula and cut off from the rest of Europe by
one of the highest mountain ranges in the continent, it is far from
having a natural unity. In terms of the average height of the land-
mass, Spain is the highest country in Europe except for Switzerland,
largely due to an impressive series of mountain ranges that divide the
peninsula into a number of discrete areas with very limited possibili-
ties for communication between them in several cases. Thus distinct
regions appear.
Starting in the north-east, the area of modern Catalonia, with the
Ebro valley that runs into it, is largely cut off from the rest of the
peninsula by a chain of mountain ranges. In fact the most natural
lines of communication of this region are to the north, and through-
out the Middle Ages the areas immediately to the north and to the
south of the eastern end of the Pyrenees were politically and cultur-
ally linked. Moving west from the Ebro valley, across very difficult
terrain, the next major area of settlement will be found on the Meseta,
a high plateau land, less fertile and habitable than the Mediterranean