ood had made the liver
sound and firm. If they continued to find it abnormal, they argued from
this that the food and water supply found in such a place would be just
as unhealthy for man, and so they moved away and changed to another
neighbourhood, healthfulness being their chief object.

10. That pasturage and food may indicate the healthful qualities of a
site is a fact which can be observed and investigated in the case of
certain pastures in Crete, on each side of the river Pothereus, which
separates the two Cretan states of Gnosus and Gortyna. There are cattle
at pasture on the right and left banks of that river, but while the
cattle that feed near Gnosus have the usual spleen, those on the other
side near Gortyna have no perceptible spleen. On investigating the
subject, physicians discovered on this side a kind of herb which the
cattle chew and thus make their spleen small. The herb is therefore
gathered and used as a medicine for the cure of splenetic people. The
Cretans call it [Greek: hasplenon]. From food and water, then, we may
learn whether sites are naturally unhealthy or healthy.

11. If the walled town is built among the marshes themselves, provided
they are by the sea, with a northern or north-eastern exposure, and are
above the level of the seashore, the site will be reasonable enough. For
ditches can be dug to let out the water to the shore, and also in times
of storms the sea swells and comes backing up into the marshes, where
its bitter blend prevents the reproductions of the usual marsh
creatures, while any that swim down from the higher levels to the shore
are killed at once by the saltness to which they are unused. An instance
of this may be found in the Gallic marshes surrounding Altino, Ravenna,
Aquileia, and other towns in places of the kind, close by marshes. They
are marvellously healthy, for the reasons which I have given.

12. But marshes that are stagnant and have no outlets either by rivers
or ditches, like the Pomptine marshes, merely putrefy as they stand,
emitting heavy, unhealthy vapours. A case of a town built in such a spot
was Old Salpia in Apulia, founded by Diomede on his way back from Troy,
or, according to some writers, by Elpias of Rhodes. Year after year
there was sickness, until finally the suffering inhabitants came with a
public petition to Marcus Hostilius and got him to agree to seek and
find them a proper place to which to remove their city. Without delay he
made the