Short answers, pulled from the story.
Marcus Terentius Varro (116-27 BC) was a Roman scholar, politician, and writer regarded as ancient Rome's greatest scholar. Petrarch called him "the third great light of Rome" after Virgil and Cicero, and Quintilian described him as "the most learned of the Romans." He produced an estimated 74 works across some 620 books on subjects ranging from agriculture and Latin language to philosophy and architecture.
The only complete work by Varro that survives is Rerum rusticarum libri tres (Three Books on Agriculture), also known as De re rustica. He wrote it around 37 BC for his wife Fundania. It covers the management of large slave-run estates and notably contains an early observation about invisible airborne creatures causing disease in swampy areas.
Varro's Nine Books of Disciplines organized knowledge around nine liberal arts: grammar, rhetoric, logic, arithmetic, geometry, astronomy, musical theory, medicine, and architecture. Transmitted through Martianus Capella's early fifth-century allegory, later scholars reduced these to seven, dropping medicine and architecture, and those seven became the standard curriculum of the medieval schools. Pliny the Elder (c. 23-79 AD) also used the Nine Books as a direct model for his own encyclopedic work.
Varro supported Pompey and commanded one of his armies in the Ilerda campaign of 49 BC. After Pompey's defeat, Julius Caesar granted Varro two pardons, one before and one after the Battle of Pharsalus in 48 BC. Caesar appointed him to oversee Rome's public library in 47 BC. After Caesar's assassination, Mark Antony proscribed Varro, who lost much of his property, including his library.
The Varronian chronology was Varro's attempt to establish a precise year-by-year timeline of Roman history based on the traditional sequence of consuls of the Roman Republic. Despite being shown to contain errors, it became the widely accepted standard chronology largely because it was inscribed on the arch of Augustus in Rome. Though the arch no longer stands, much of the chronology survived under the name Fasti Capitolini.
Varro was born in or near Reate, the town now called Rieti in Lazio. His family was thought to be of equestrian rank. He maintained close ties to the region throughout his life, owning a large farm on the Reatine plain, reportedly near Lago di Ripasottile, into old age. He studied under the Roman philologist Lucius Aelius Stilo and later at Athens under the philosopher Antiochus of Ascalon.