Decimus or Decimius Magnus Ausonius (; c. 310 – c. 395) was a Roman poet and teacher of rhetoric from Burdigala in Aquitaine, modern Bordeaux, France. For a time he was tutor to the future emperor Gratian, who afterwards bestowed the consulship on him. His best-known poems are Mosella, a description of the river Moselle, and Ephemeris, an account of a typical day in his life. His many other verses show his concern for his family, friends, teachers, and circle of well-to-do acquaintances and his delight in the technical handling of meter.
Decimius Magnus Ausonius was born c. 310 in Burdigala, the son of Julius Ausonius (c. AD 290-378), a physician of Greek ancestry, and Aemilia Aeonia, daughter of Caecilius Argicius Arborius, descended on both sides from established, land-owning Gallo-Roman families of southwestern Gaul. Ausonius was given a strict upbringing by his aunt and grandmother, both named Aemilia. He received an excellent education at Bordeaux and at Toulouse, where his maternal uncle, Aemilius Magnus Arborius, was a professor. Ausonius did well in grammar and rhetoric, but professed that his progress in Greek was unsatisfactory. When his uncle was summoned to Constantinople to tutor one of the sons of emperor Constantine I, Ausonius accompanied him to the capital.
Having completed his studies, he trained for some time as an advocate, but he preferred teaching. In 334 he became a 'grammaticus' (instructor) at a school of rhetoric in Bordeaux, and afterwards a 'rhetor' or professor. His teaching attracted many pupils, some of whom became eminent in public life. His most famous pupil was the poet Paulinus, who later became a Christian and Bishop of Nola.
After thirty years of this work Ausonius was summoned by emperor Valentinian I to teach his son, Gratian, the heir-apparent. When Valentinian took Gratian on the German campaigns of 368-9, Ausonius accompanied them. In recognition of his services emperor Valentinian bestowed on Ausonius the rank of quaestor. Gratian liked and respected his tutor, and when he himself became emperor in 375 he began bestowing on Ausonius and his family the highest civil honors. That year Ausonius was made Praetorian Prefect of Gaul, campaigned against the Alemanni and received as part of his booty a slave-girl, Bissula (to whom he addressed a poem), while his father, though nearly ninety years old, was given the rank of Prefect of Illyricum. In 376 Ausonius's son, Hesperius, was made proconsul of Africa. In 379 Ausonius was awarded the consulate, the highest Roman honor.
In 383 the army of Britain, led by Magnus Maximus, revolted against Gratian and assassinated him at Lyons; and when emperor Valentinian II was driven out of Italy, Ausonius retired to his estates near Burdigala (now Bordeaux) in Gaul.  When Magnus Maximus was overthrown by emperor Theodosius I in 388, Ausonius did not leave his country estates. They were, he says, his nidus senectutis, the 'nest of his old age', and there he spent the rest of his days, composing poetry and writing to many eminent contemporaries, several of whom had been his pupils. His estates supposedly included the land now owned by Château Ausone, which takes its name from him.
Ausonius appears to have been a late and perhaps not very enthusiastic convert to Christianity. He died about 395. His grandson, Paulinus of Pella, was also a poet; his works attest to the devastation which Ausonius's Gaul would face soon after his death.
Although admired by his contemporaries, the writings of Ausonius have not since been ranked among Latin literature's finest. His style is easy and fluent, and his Mosella is appreciated for its evocation of the life and country along the River Moselle; but he is considered derivative and unoriginal. Edward Gibbon pronounced in his Decline and Fall of the Roman Empire that "the poetical fame of Ausonius condemns the taste of his age." However, his works have several points of interest:
2. His contribution to the carpe diem topic is also widely known:
Collige, virgo, rosas, dum flos novus et nova pubes
Gather, girl, roses while the flower is fresh and fresh is youth,
|--Epigrammata: «Rosae» 2:49|
Itque reditque viam totiens | uteroque recusso
Back and forth he plies his path and, the cavity reverberating,
....renowned is Celbis for glorious fish, and that other, as he turns his mill-stones in furious revolutions and drives the shrieking saws through smooth blocks of marble, hears from either bank a ceaseless din...
The excerpt sheds new light on the development of Roman technology in using water power for different applications. It is one of the rare references in Roman literature of water mills used to cut stone, but is a logical consequence of the application of water power to mechanical sawing of stone (and presumably wood also). Earlier references to the widespread use of mills occur in Vitruvius in his De Architectura of circa 25 BC, and the Naturalis Historia of Pliny the Elder published in 77 AD. Such applications of mills were to multiply again after the fall of the Empire through the Middle Ages into the modern era. The mills at Barbegal in southern France are famous for their application of water power to grinding grain to make flour and were built in the 1st century AD. They consisted of 16 mills in a parallel sequence on a hill near Arles.
The construction of a saw mill is even simpler than a flour or grinding mill, since no gearing is needed, and the rotary saw blade can be driven direct from the water wheel axle, as the example of Sutter's Mill in California shows. However, a different mechanism is shown by the sawmill at Hieropolis involving a frame saw operated through a crank and connecting rod.