(b. San Miniato, Italy, 13 April 1541; d. Rome, Italy, 25 June 1593)
medicine, natural sciences.
Mercati was the elder son of Pietro Mercati, a doctor, and Alfonsina Fiaminga. He received his early education from his father and later enrolled at the University of Pisa, where he studied under Cesalpino. Possibly as a result of the specialized knowledge he received from Cesalpino, Mercati was called by Pope Pius V to direct the Vatican botanical garden, a post he retained under Gregory XIII and Sixtus V. He was very active in botany and contributed greatly to the development of the simples section of the botanical garden. He was early famous for his scientific achievements; when he was only twenty-seven, the future Grand Duke Ferdinand I of Tuscany honored him by elevating his family into the ranks of the Florentine aristocracy, while the same privilege was bestowed on him the following year by the Roman Senate. Pope Gregory XIII named him a member of the “pontifical family,” and Mercati showed his gratitude by caring for the pope during his final illness. For Gregory XIII, Mercati wrote Istruzione sopra la peste (Rome, 1576), with the addition “Tre altre istruzioni sopra i veleni occultamente ministrati, podagra e paralisi”—which is, however, of limited scientific value. Pope Sixtus V held Mercati in great esteem and created him apostolic protonotary. He also sent him to Poland with Cardinal Aldobrandini (later Clement VIII) on a mission to King Sigismund III. It was during that journey that Mercati began writing from memory a book on the obelisks of Rome; it was published at Rome in 1589 under the title Degli obelischi di Roma. Clement VIII made Mercati chief physician and knight of the Order of Santo Spirito in Sassia.
Mercati suffered from bladder and kidney stones and gout. In 1582 he recovered from an attack of renal colic; he had another four years later. On the advice of his friend Filippo Neri he retired to the Oratorian monastery at Santa Maria in Vallicella, where he could receive better care. Again he recovered; but following a third attack in 1593 he died, at the age of fifty-two. He was treated by Filippo Neri and by his teacher Cesalpino, whom he had called to Rome years previously and for whom he had procured appointments as papal physician and professor at the University of Rome. An autopsy on Mercati, possibly carried out by Cesalpino himself, showed the existence of two stones in the ureters, about sixty in the kidneys, and thirty-six in the gallbladder. Mercati was buried in the church of Santa Maria in Vallicella, in the tomb of the Mediobarba family. He had been a friend and correspondent not only of Filippo Neri and of famous cardinals, but also of persons renowned in the arts and sciences, including Marsilio Cognati, Pier Angelo Bargeo, Latino Latini, Girolamo Mercuriale, Aldrovandi, and Melchior Wieland (better known as Guilandinus). A portrait of Mercati engraved by Benoit Fariat (after Tintoretto) is the frontispiece of his Metallotheca.
As a naturalist Mercati’s greatest interest lay in collecting minerals and fossils: this collection later formed the basis of the work that has made him famous: Metallothica. Opus postumum, auctoritate et munificentia Clementis undecimi pontificis maximi e tenebris in lucem eductum; opera autem et studio Joannis Mariae Lancisii archiatri pontificii illustratum (Rome, 1717).
Mercati was a good mineralogist and one of the founders of paleontology. He understood the true origin of stone implements, which in his day were considered to be the product of lightning. In his book he described, besides the Vatican collection of minerals, some stones of animal origin and the bladder stones that had been found by Lancisi during the autopsy of Pope Innocent XI.
Mercati’s book is illustrated by beautiful copper engravings which, with the manuscript of the work, were rediscovered by Carlo Roberto Dati in the eighteenth century.
In addition to Mercati’s writings mentioned above, on Mercati and his work see P. Capparoni, “Michele Mercati (1541–1593),” in Profili bio-bibliografici di medici e naturalisti celebri italiani dal secolo XV al secolo XVIII (Rome, 1932), pp. 48–50; E. Gurlt, Geschichte der Chirurgie und ihrer Ausübung, II (repr. Hildesheim, 1964), 482–483; W. Haberling and J. L. Pagel, “Mercati, Michele,” in Lexicon der hervorragen den ärzte aller Zeiten und Völker, W. Haberlinng, F. Hubotter, and H. Vierordt, eds., 2nd ed., IV (Berlin-Vienna, 1932), 169–170; and G. Montalenti, Storia delle scienze, N. Abbagnano, ed., III pt. 1 (Turin, 1962), 353.