irtues of the mixture dissolved. This defect, in
turn, may arise from the cooling properties of moist winds and breezes
blowing upon the body. In the same way, increase or diminution of the
proportion of air or of the earthy which is natural to the body may
enfeeble the other elements; the predominance of the earthy being due to
overmuch food, that of air to a heavy atmosphere.

7. If one wishes a more accurate understanding of all this, he need only
consider and observe the natures of birds, fishes, and land animals, and
he will thus come to reflect upon distinctions of temperament. One form
of mixture is proper to birds, another to fishes, and a far different
form to land animals. Winged creatures have less of the earthy, less
moisture, heat in moderation, air in large amount. Being made up,
therefore, of the lighter elements, they can more readily soar away into
the air. Fish, with their aquatic nature, being moderately supplied with
heat and made up in great part of air and the earthy, with as little of
moisture as possible, can more easily exist in moisture for the very
reason that they have less of it than of the other elements in their
bodies; and so, when they are drawn to land, they leave life and water
at the same moment. Similarly, the land animals, being moderately
supplied with the elements of air and heat, and having less of the
earthy and a great deal of moisture, cannot long continue alive in the
water, because their portion of moisture is already abundant.

8. Therefore, if all this is as we have explained, our reason showing us
that the bodies of animals are made up of the elements, and these
bodies, as we believe, giving way and breaking up as a result of excess
or deficiency in this or that element, we cannot but believe that we
must take great care to select a very temperate climate for the site of
our city, since healthfulness is, as we have said, the first requisite.

9. I cannot too strongly insist upon the need of a return to the method
of old times. Our ancestors, when about to build a town or an army post,
sacrificed some of the cattle that were wont to feed on the site
proposed and examined their livers. If the livers of the first victims
were dark-coloured or abnormal, they sacrificed others, to see whether
the fault was due to disease or their food. They never began to build
defensive works in a place until after they had made many such trials
and satisfied themselves that good water and f