Johann Faber was born the son of Protestant parents in Bamberg in 1574. When he was one year old he was orphaned by an epidemic of the plague. He was raised and educated in the Catholic faith by his cousin Philip Schmidt. He studied medicine at the University of Würzburg and graduated in 1597. In order to continue his studies he moved to Rome in 1598, where he worked as a doctor in the hospital of Santo Spirito in Sassia. His practical studies of anatomy proceeded from direct observation of the human body. He later turned exclusively to the study of animal anatomy. In 1600 he was appointed to the chair of Botany and of Anatomy at the Sapienza University of Rome. In the same year he became the director of the Papal botanical garden.
His interests in natural philosophy continued to develop after his return to Rome. Here he was a frequent visitor to the pharmacy of his friend the Dutch botanist Enrico Corvino at the sign of the Imperial Eagle in Montegiordano, where many of the city's artists and physicians gathered. Faber was also friendly with Peter Paul Rubens who was working in the city until 1608, as well as other painters and miniaturists. Corvino was to become a member of the Accademia dei Lincei in 1611, and Faber came to know a number of the men who were involved in its work, including Federico Cesi, its founder, Johann Schreck and Theophilus Müller. On 29 October 1611 Faber himself became a member. December 1612 saw the visit to Rome of Johann Gottfried von Aschhausen, Prince-Bishop of Bamberg. Faber hoped to make him a gift of a telescope, but was unable to do so owing to the difficulties Galileo as experiencing in producing lenses of sufficiently high quality. Nevertheless he was able to use the visit to help foster academic projects in Germany, ensuring that the Bishop was given a number of books written by members of the Accademia, and a sample volume of Hernandez's Mexicanarum plantarum which Cesi had charged Schreck and Faber with editing. Faber's work, with a dedication to Francesco Barberini, was finally published in 1628 under the title Animalia Mexicana, while the edited version of Hernandez' full original was published only after his death, in 1651.
Giovanni Faber has been credited with giving the microscope its name. In 1609 fellow Lincean Galileo developed a compound microscope with a convex and a concave lens which he called the occhiolino, the "little eye". In 1624 Galileo presented his occhiolino to Prince Federico Cesi, founder of the Accademia dei Lincei. One year later Giovanni Faber coined the word microscope from the Greek words μικρόν meaning "small", and σκοπεῖν meaning "to look at". The word was meant to be analogous with telescope, another word coined by the Linceans.
Family
In 1608 Faber became a naturalised Roman by adopting the legal status of "civis romanus": on 19 August 1612 he married Maria Anna Hyrler, who was herself born in Rome to German parents. Faber died on 17 September 1629 and was buried, in accordance with his last wish, in the church of Santa Maria dell'Anima next to his wife who had died some two years previously. He was survived by several children; Maria Vittoria, Maria Maddalena and Giano Domenico.