The Natural History () is a work by Pliny the Elder. The largest single work to have survived from the Roman Empire to the modern day, the Natural History compiles information gleaned from other ancient authors. Despite the work's title, its subject area is not limited to what is today understood by natural history; Pliny himself defines his scope as "the natural world, or life". It is encyclopedic in scope, but its structure is not like that of a modern encyclopedia. It is the only work by Pliny to have survived, and the last that he published. He published the first 10 books in AD 77, but had not made a final revision of the remainder at the time of his death during the AD 79 eruption of Vesuvius. The rest was published posthumously by Pliny's nephew, Pliny the Younger. The work is divided into 37 books, organised into 10 volumes. These cover topics including astronomy, mathematics, geography, ethnography, anthropology, human physiology, zoology, botany, agriculture, horticulture, pharmacology, mining, mineralogy, sculpture, art, and precious stones. Pliny's Natural History became a model for later encyclopedias and scholarly works as a result of its breadth of subject matter, its referencing of original authors, and its index. Overview Pliny's Natural History was written alongside other substantial works (which have since been lost). Pliny (AD 23–79) combined his scholarly activities with a busy career as an imperial administrator for the emperor Vespasian. Much of his writing was done at night; daytime hours were spent working for the emperor, as he explains in the dedicatory preface addressed to Vespasian's elder son, the future emperor Titus, with whom he had served in the army (and to whom the work is dedicated). As for the nocturnal hours spent writing, these were seen not as a loss of sleep but as an addition to life, for as he states in the preface, Vita vigilia est, "to be alive is to be watchful", in a military metaphor of a sentry keeping watch in the night. Pliny claims to be the only Roman ever to have undertaken such a work, in his prayer for the blessing of the universal mother: Hail to thee, Nature, thou parent of all things! and do thou deign to show thy favour unto me, who, alone of all the citizens of Rome, have, in thy every department, thus made known thy praise. The Natural History is