social duties to be founded in the unalterable
dictates of virtue; but it was easier to demonstrate the truth of the
principles which he maintained, than to enforce their observance, while
the morals of mankind were little actuated by the exercise of reason
alone.

The science chiefly cultivated at this period was rhetoric, which appears
to have differed considerably from what now passes under the same name.
The object of it was not so much justness of sentiment and propriety of
expression, as the art of declaiming, or speaking copiously upon any
subject. It is mentioned by Varro as the reverse of logic; and they are
distinguished from each other by a simile, that the former resembles the
palm of the hand expanded, and the latter, contracted into the fist. It
is observable that logic, though a part of education in modern times,
seems not to have been cultivated amongst the Romans. Perhaps they were
apprehensive, lest a science which concentered the force of argument,
might obstruct the cultivation of that which was meant to dilate it.
Astronomy was long before known in the eastern nations; but there is
reason to believe, from a passage in Virgil [269], that it was little
cultivated by the Romans; and it is certain, that in the reformation of
the calendar, Julius Caesar was chiefly indebted to the scientific
knowledge of (158) Sosigenes, a mathematician of Alexandria. The laws of
the solar system were still but imperfectly known; the popular belief,
that the sun moved round the earth, was universally maintained, and
continued until the sixteenth century, when the contrary was proved by
Copernicus. There existed many celebrated tracts on mathematics; and
several of the mechanical powers, particularly that of the lever, were
cultivated with success. The more necessary and useful rules of
arithmetic were generally known. The use of the load-stone not being as
yet discovered, navigation was conducted in the day-time by the sun, and
in the night, by the observation of certain stars. Geography was
cultivated during the present period by Strabo and Mela. In natural
philosophy little progress was made; but a strong desire of its
improvement was entertained, particularly by Virgil. Human anatomy being
not yet introduced, physiology was imperfect. Chemistry, as a science,
was utterly unknown. In medicine, the writings of Hippocrates, and other
Greek physicians, were in general the standard of practice; but the
Materia