Natural History
Pliny's last work, according to his nephew, was the Naturalis Historia, an encyclopedia into which he collected much of the knowledge of his time. Answers concerning the date of its publication, composition, or when he started or stopped work upon it, depend on the questions asked.
The encyclopedia utilizes some material from his memories of earlier times and from his prior works, such as the book on Germany. There is no evidence that he had planned to use this material in an encyclopedia later in his career. Most of the references in the encyclopedia must have come from his extracts, which he kept on an ongoing basis, hiring a reader and a secretary to keep them, and furnishing that secretary with gloves in winter so that his writing hand would not stiffen with cold. The extracts collected for this purpose filled rather less than 160 volumes, which Larcius Licinus, the praetorian legate of Hispania Tarraconensis, vainly offered to purchase for 400,000 sesterces. That would have been in 73/74 (see above). At his death Pliny left the 160 volumes to his nephew. When composition began is unknown. Since he was preoccupied with his other works under Nero and then had to finish the history of his times, it is unlikely he began before 70. The procuratorships offered the ideal opportunity for an encyclopedic frame of mind. The date of an overall composition cannot be assigned to any one year. The dates of different parts must be determined, if they can, by philological analysis (the "post-mortem" of the scholars).
The closest known event to a single publication date; that is, when the manuscript was probably released to the public for borrowing and copying, and was probably sent to the Flavians, is the date of the Dedication in the first of the 37 books. It is to the "emperor" Titus. As Titus and Vespasian had the same name, Titus Flavius Vespasianus, earlier writers hypothesized a dedication to Vespasian. Pliny's mention of a brother (Domitian) and joint offices with a father, calling that father "great", points certainly to Titus. Since Titus is addressed as emperor, apparently Vespasian had died, in which case the date would be 79.
However, Pliny says that Titus had been consul six times. The first six consulships of Titus are in 70, 72, 74, 75, 76 and 77, all conjointly with Vespasian, which brings the date of the Dedication to 77. In that year Vespasian was 68. He had been ruling conjointly with Titus for some years, which may be why he allowed Pliny to call Titus "emperor" and dedicate the work to him. Aside from minor finishing touches, the work in 37 books was completed in AD 77. It would be unsubstantiated to presume that it was written entirely in 77 or that Pliny was finished with it then. Moreover, the dedication could have been written before publication, and it could have been published either privately or publicly earlier without dedication. The only certain fact is that Pliny did no further work on it after AD 79.
The Naturalis Historia is one of the largest single works to have survived from the Roman empire to the modern day and purports to cover the entire field of ancient knowledge, based on the best authorities available to Pliny. He claims to be the only Roman ever to have undertaken such a work. It encompasses the fields of botany, zoology, astronomy, geology and mineralogy as well as the exploitation of those resources. It remains a standard work for the Roman period and the advances in technology and understanding of natural phenomena at the time. Some technical advances he discusses are the only sources for those inventions, such as hushing in mining technology or the use of water mills for crushing or grinding corn. Much of what he wrote about has been confirmed by archaeology. It is virtually the only work which describes the work of artists of the time, and is a reference work for the history of art.
The work became a model for all later encyclopedias in terms of the breadth of subject matter examined, the need to reference original authors, and a comprehensive index list of the contents. Interspersed amongst the agricultural entries are several recipes and references to common methods of preparing food. Some of these have been collected in the book Roman Cookery. The work is dedicated to the Emperor Titus, son of Pliny's close friend, the emperor Vespasian, in the first year of Titus' reign. It is the only work by Pliny to have survived, and the last that he published, lacking a final revision at his sudden and unexpected death in the AD 79 eruption of Vesuvius.
Read more about this topic: Pliny The Elder