Giovanni Marliani

Background

Giovanni Marliani was born in 1420 in Milan, Duchy of Milan (now Lombardia, Italy) to the family of a Milanese noble, Cantello Marliani. There is little information on Marliani’s early life.

Education

Marliani studied medicine and probably arts at the University of Pavia under the tutelage of Biagio Pelacani of Parma. He became a doctor in 1440.

Career

In 1440 Giovanni Marliani was elected to the College of Physicians in Milan. From 1441 to 1447 Marliani taught natural philosophy and “astrologia” at Pavia, and lectured on the physics of Bradwardine and Albert of Saxony. Under the short-lived Ambrosian Republic, he left Pavia for the University of Milan (1447-1450), where he taught medicine. He was also appointed to civic office. Following the collapse of the Ambrosian Republic, Marliani returned to Pavia, where he added medicine to his previous lectureships, eventually acquiring (1469) the chair of medical theory. His salaries testify to a successful career: in 1441 Marliani earned 40 florins a year; in 1447, 200 florins; in 1463, 500 florins, plus, by a secret arrangement with Duke Francesco I Sforza, an additional 150 florins. Later a special chair was set up for the Marliani family, to be held first by Giovanni’s son, Paolo, in 1483. Two other sons, Girolamo and Pietro, also lectured at the university. The fortune of the family was sealed with Marliani’s appointment (probably in 1472) as a court physician to Galeazzo Maria Sforza. He also enjoyed the favor of the latter’s successor, Gian Galeazzo.

Marliani’s works were printed at Pavia in 2 volumes in 1482. The dates of composition are in parentheses. The writings are Tractatus de reactione (1448); In defensionem Tractatus de reactione (against Gaetano da Thiene, 1454-1456); “Annotationes in librum de instanti Petri Mantuani,” unpub. work in Biblioteca Vaticana, MS Vat. Lat. 2225 (see Thorndike, below); Probatio cuiusdam sententiae calculatoris de motu locali (1460); Disputatio cum Joanne de Arculis (1461); Difficultates missae Philippo Adiute Veneto (before 1464); “Algorismus de minutiis” (before 1464).

Achievements

• Marliani was the first to empirically prove that hot water freezes faster than cold water. Leonardo da Vinci is known to have studied Marliani's science publications thoroughly, although he did not always agree with his findings.

Works

More photos

• book

  • Vrbis Romae topographia 1544
  • Disputatio cum Johanne Arculano de diversis materiis ad philosophiam et medicinam pertinentibus; Opuscula 1482
  • Quaestio de proportione motuum in velocitate 1482
  • Le antichita di Roma di Bartolomeo Marliani caualier di San Pietro. Tradotte in lingua volgare da Hercole Barbarasa 1622
  • Antiquae Romae topographia libri septem 1534

Views

Despite his strongly Scholastic views, Marliani was well regarded by humanists of the time. Pico della Mirandola called him the greatest mathematician of the age, and Francesco Filelfo and Marliani corresponded on medical and Scholastic matters. Giorgio Valla, who studied medicine and mathematics under Marliani at Pavia, translated the Problemata of Alexander of Aphrodisias at the urging of his teacher. Valla stated that Marliani owned a copy of Jacobus Cremonensis’ translation of Archimedes, but the sole extant mathematical work by Marliani is on common fractions and shows little originality or knowledge of Greek mathematics. Valla’s later work, however, abandoned the Scholastic physics of his teacher in favor of classical mathematics. Most Renaissance humanists and mathematicians shared Valla’s preference.

Three works by Marliani deal with heat in a strongly Aristotelian fashion. The heating or cooling action is regarded as a special case of motion and thus subject to Aristotle’s mistaken law of motion. In the early treatise De reactione, for instance, reaction (meaning the capacity of an agent to be affected by its patient) is analyzed in terms of active and resistive powers, as though it were motion. Although Marliani admits his debt to Jacopo da Forli and others, he systematically rejects many of these predecessors” arguments in favor of some rather tortuous arguments of his own. (His criticisms soon involved Marliani in a polemic with Gaetano da Thiene.) Two main points of interest appear in the De reactione, although neither is original. These are Marliani’s distinction between intensity of heat (temperature) and its extension (quantity of heat) and his use of a numerical scale to represent the intensity. This scale consists of eight degrees of calidity and its coextensive frigidity (F° = 8 – C°) The Marliani scale should not, perhaps, be taken as a forerunner of the thermometric scale, since it depends conceptually upon an Aristotelian qualitative distinction between heat and cold.

The Disputatio cum Joanne de Arculis discusses the reduction of hot water (that is, whether hot water is cooled by an intrinsic tendency or an extrinsic agent, such as its container). Marliani again applies his Aristotelian principle relating action and resistance to the quantity of heat and cold present. In contrast with his Avicennist opponent Giovanni Arcolani of Verona, who argues for intrinsic reduction, Marliani maintains that at any temperature, hot and cold components of the water are in equilibrium and thus cannot act upon one another. Hence, the cooling agent must be external. He also concludes that the shapes of the agent and the patient, and their distance apart, are factors in a heat action.

De caliditate corporum humanorum combines Marliani’s knowledge of medicine and physics. Distinguishing between heat intensity (temperature) and its extension (the quantity of “natural” heat produced by the body), Marliani concludes that the human body, while increasing its natural heat in the winter, maintains a more or less constant temperature through most of its parts. Nevertheless, he still feels obliged (despite a youthful repudiation) to accept the notion of antiperistasis (the increase of intensity when a body is suddenly surrounded by its contrary quality), which underlay the arguments for a varying body temperature.

Marliani’s writings on mechanics center on two main problems of Scholastic physics. In the Probatio calculatoris the kinematic mean-speed theorem of accelerated motion is outlined with some clear proofs. Of more significance is the De proportione motuum, designed to solve a paradox in Aristotle’s law of motion. The Aristotelian law held velocity to be proportional to the ratio of the moving power to the resistance. A paradox arose when the moving power was equal to the resistance. Obviously no motion should then occur, but the ratio in the law gave a positive value to the velocity in this case. Bradwardine’s law tried to eliminate the paradox by stating that the “proportions of velocities in motions follow the proportion of the power of the motor, to the power of the thing moved.” Using the proportion of proportions calls for a geometrical increase in the ratio of force to resistance. Bradwardine, however, used terms which can denote either an arithmetical or geometrical increase - for instance, “dupla,” to mean “deouble” or “squared.” Misled by this ambiguous terminology to assume that Bradwardine had fallen into the same trap as Aristotle, Marliani severely condemned the former and advanced his own law that velocity is proportional to the excess of the motor power over the resistance. Nevertheless, Bradwardine’s law remained acceptable to most Renaissance Aristotelian philosophers.

Marliani’s career and works suggest that he was a competent Scholastic physicist and an adept publicist of the calculatores and French Scholastics in Italy. Influential among philosophers (his De reactione was later discussed by Pietro Pomponazzi), Marliani seems to have stayed largely outside the mainstream of Italian Renaissance mathematics. Much of his great reputation seems also to have rested on his position as physician to the Sforzas.

Connections

Giovanni Marliani was supposedly married. In any case, he had at least three sons: Paolo, Girolamo, and Pietro.

Father:

Cantello Marliani

Son:

Paolo Marliani

Son:

Girolamo Marliani

Son:

Pietro Marliani

employer:

Francesco Sforza

References

• Dictionary of Scientific Biography: Volumes 9 & 10
  1980