Physics 157
caring for the young they have produced, until such time as the young
can defend themselves? Although fish are said to abandon their eggs once
they have laid them, it is easy for them to be supported by the water
and to hatch in it. Turtles, though, and crocodiles are said to bear their
young on land, then bury the eggs and go away, leaving them to be born
and raised all by themselves. But hens and other birds seek a peaceful
place for bearing their young and there build dwellings and nests, making
them as soft as possible a support for the eggs in order to promote their
survival. And when the chicks hatch, [the adults] protect them and cuddle
them with their wings so that the cold will not hurt the young; or if it
is hot, they shade them from the sun. But when the chicks can first make
use of their wings, then their mothers accompany them on their flights
but otherwise need care for them no further. 130. Human care and
intelligence is also a factor contributing to the preservation and well-
being of several species of animals and of plants born from the earth;
for there are many kinds of domesticated animals and plants which could
not survive without the care of human beings.
The agricultural activities of men and their success are made easier
by a variety of different factors in different regions. The Nile irrigates
Egypt, keeping the land flooded all summer until it recedes and leaves
the fields softened and muddy for the planting season. The Euphrates
makes Mesopotamia fertile by bringing new soil to the fields every year.
And the Indus River, the largest of all, not only fertilizes the fields and
softens them but even sows them; for it is said to bring with its waters
a great quantity of seeds which resemble those of grain. 131. I could
mention many other noteworthy things from a variety of areas, and many
regions all of which are fertile for different kinds of crops.
But how great is nature's generosity! She produces so many different
kinds of appetizing food, at all different times of the year, that we are
always delighted by both its abundance and its novelty. She has given
us the Etesian winds; how fitting to their season and how salutary not
just for mankind but also for the animal species and even for plants
which grow from the earth. Excessive heat is moderated by their [gentle]
breath and they also help our ships to steer a swift and certain course
at sea. I must pass over many points. 132. For the blessings provided
by rivers are beyond counting, as are those of the tides which ebb and
flow, of the mountains clad in forests, of salt pools found far from the
sea shore, regions where the very soil teems with medicinal substances,
and finally, [so are the blessings] of numberless crafts which are essential
for our life and well-being. Even the alternation of day and night helps
to preserve animal life by setting aside different times for action and for
rest. Thus from every angle and by every line of reasoning, our minds