It is stressed in the passage that the Mediterranean ____ .

Those who visit the Mediterranean are invariably
impressed with its unity. Everywhere it is the same, for
the shades of difference here is less important than
the resemblances. Yet this unity is the result of
aggressive contrast; sea and mountain, sea and
desert, sea and ocean! In these respects the
Mediterranean is very different from either central
Europe, or high tablelands of Asia, the Syrian and
Saharan deserts, or even the Atlantic Ocean.