Pliny the Elder (c. AD 23–79)

A 15th-century manuscript from Siena, Italy, of the Historia Naturalis, an immense encyclopedia probably completed in AD 77 by the Roman writer Pliny the Elder. The Historia makes no distinction between the real and the imaginary, but provides a fascinating insight into Roman learning in the 1st century AD.

Roman scientific encyclopedist and historian. Many of his works have been lost, but in Historia naturalis/Natural History, probably completed AD 77, Pliny surveys all the known sciences of his day, notably astronomy, meteorology, geography, mineralogy, zoology, and botany.

Pliny states that he has covered 20,000 subjects of importance drawn from 100 selected writers, to whose observations he has added many of his own. Botany, agriculture, and horticulture appear to interest him most. To Pliny the world consisted of four elements: earth, air, fire, and water. The light substances were prevented from rising by the weight of the heavy ones, and vice versa. This is the earliest theory of gravity.

Pliny was born in Como, completed his studies in Rome and took up a military career in Germany, where he became a cavalry commander and friend of Vespasian. He kept out of harm's way while Nero was on the throne, but when in AD 69 Vespasian was made emperor, Pliny returned to Rome and took up various public offices. In AD 79 he was in command of a fleet in the bay of Naples when the volcano Vesuvius erupted. He was killed by poisonous fumes.

According to Pliny, the Earth was surrounded by seven stars: the Sun, the Moon, Mercury, Venus, Mars, Jupiter, and Saturn. Pliny took the Moon to be larger than the Earth, since it obscured the Sun during an eclipse.