ay, and the _ostium_ or doorway with its _janua_, you
saw in front of you the impluvium, into which the rainwater fell from
the _compluvium_, i.e. the square opening in the roof with sloping
sides; on either side were recesses (_alae_), which, if the family
were noble, contained the images of the ancestors. Opposite you was
another recess, the _tablinum_, opening probably into a little garden;
here in the warm weather the family might take their meals.

This is the atrium of the old Roman house, and to understand that
house nothing more is needed. And indeed architecturally, the atrium
never lost its significance as the centre of the house; it is to the
house as the choir is to a cathedral.[381] And it is easy to see how
naturally it could develop into a much more complicated but convenient
dwelling; for example, the alae could be extended to form separate
chambers or sleeping-rooms, the tablinum could be made into a
permanent dining-room, or such rooms could be opened out on either
side of it. A second story could be added, and in the city, where
space was valuable, this was usually the case. The garden could be
converted, after the Greek fashion, and under a Greek name, into a
_peristylium_, i.e. an open court with a pretty colonnade round it,
and if there were space enough, you might add at the rear of this
again an _exedra_, or an _oecus_, i.e. open saloons convenient for
many purposes. Thus the house came to be practically divided into two
parts, the atrium with its belongings, i.e. the Roman part, and the
peristylium with its developments, forming the Greek part; and the
house reflects the composite character of Roman life in its later
period, just as do Roman literature and Roman art. The Roman part was
retained for reception rooms, and the Lar, the Penates, and Vesta,
with their respective seats, retired into the new apartments for
privacy. When the usual crowd of morning callers came to wait upon a
great man, they would not as a rule penetrate farther than the atrium,
and there he might keep them waiting as long as he pleased. The Greek
part of the house, the peristylium and its belongings, was reserved
for his family and his most intimate friends. In Pompeii, which was an
old Greek town with Roman life and habits superadded, we find atrium
and peristylium both together as early as the second century B.C.[382]
At what period exactly the house of the noble in Rome began thus to
develop is not so certain. But by