If you glance at the study of mathematics, astronomy, and medicine among the Romans prior to the time of Greek influence, you find that next to nothing had been accomplished. Their method of field measurement was far less developed than the ancient Egyptian geometry, and even for it (as well as for their system of numerals) they were indebted to the Etruscans. The history of astronomy has nothing to record of scientific accomplishment on the part of the Romans. They reckoned time by months, and in the earlier period kept a rude tally of the years by driving nails into a statue of Janus, the ancient sun-god. As we shall see, they were unable to regulate the calendar. Again, so far were they from contributing to the development of medicine that they had no physicians for the six hundred years preceding the coming of Greek science. A medical slave acted as overseer of the family health, and disease was combated in primitive fashion by prayers and offerings to various gods, who were supposed to furnish general health or to influence the functions of the different parts of the body. So rude was the native culture of the Romans that it is doubtful whether they had any schools before the advent of Greek learning. The girls were trained by their mothers, the boys either by their fathers or by some master to whom they were apprenticed. The Greeks were conquered by the Romans in 146 B.C., but before that time Roman life and institutions had been touched by Hellenic culture. Cato the Censor (who died in 149 B.C.) and other conservatives tried in vain to resist the invasion of Greek science, philosophy, and refinement. After the conquest of Greece the master became pupil, and the conqueror was taken captive. The Romans, however, never rose to preëminence in science or the fine arts. A further development in technology corresponded more closely to their national needs, and in this field they came undoubtedly to surpass the Greeks. Bridges, ships, military roads, war-engines, aqueducts, public buildings, organization of the State and the army, the formulation of legal procedure, the enactment and codification of laws, were necessary to secure and maintain the Empire. The use in building construction of a knowledge of the right-angled triangle as well as other matters known to the Egyptians and Babylonians, and Archimedes' method of determining specific gravity were of peculiar interest to the practical Romans.