Giovanni Alfonso Borelli (1608-1679)


   “I undertook this work, not only to illustrate and enrich the part devoted to Physics by mathematical demonstrations but also to enlist anatomy into Physics and Mathematics not less than Astronomy.”


An Italian-born mathematician, biologist, and astronomer, he was an Italian Renaissance physicist who sought to make mechanical laws applicable to all physiological phenomena. Borelli, who studied at Padua under Galileo, regarded the human body essentially as a machine whose functions could be explained by the laws of physics. He mentored Marcello Malpighi, who went on to become the father of microscopical anatomy, and was instrumental in the foundation of the Iatrophysical school of thought, which used mathematical and physical principles to understand the material world. At his laboratory in Pisa, Borelli made a number of important discoveries about respiration, circulation, and the muscular system. De Motu Animalium is an illustrated study of human and animal muscular exertion.

Title Page of 2nd edition
De motu animalium (2 volumes)
Borelli, Giovanni Alfonso
Published: 1685

He was born in Naples in 1608. His De Motu Animalium, published in 1680, extended to biology the rigorous analytical methods developed by Galileo in the field of mechanics. Borelli calculated the forces required for equilibrium in various joints of the human body well before Newton published The Laws of Motion. Borelli was the first to understand that the levers of the musculoskeletal system magnify motion rather than force, so that muscles must produce much larger forces than those resisting the motion.  Borelli became consumed in the physical laws of nature and the human body. His work served as a monumental contribution to ascertain, in depth and with undiminished accuracy, the basic biomechanical principles of the human body.
Borelli died in Rome on December 31, 1679, but his impressive body of original work helped inspire a great number of future scientists, microscopists, and inventors. The highest honor bestowed by the American Society of Biomechanics is the Giovanni Borelli Award.
He was often underappreciated in the conversation of significant men of learning during the Scientific Revolution. Like many of the historic philosophers and scientists of his time, Borelli focused on a wide spread of sciences and questions; a stark contrast to the highly-specialized fields of science today. Borelli did not have the luxuries to exhaust years of research and resources on a single topic, which would lead to a revolutionary answer to an already well-understood topic. He additionally neither had expansive archives of previous research and answers to work from, nor the incredible network of communication enjoyed today.
Giovanni Alfonso Borelli made outstandingly influential discoveries across many fields, using literature only readily available to him, countless hours of observation through a microscope; over many sleepless nights aided only by candlelight. One could write essays upon essays unravelling the extensive research and discoveries made by Borelli over his academic career; however, his most influential and detailed discoveries were made in the fields of biology and more specifically anatomy.
Aided by the most rudimentary microscopes, Borelli was able to lay out specific actions of muscles both in humans and in animals, identify and define the constituents of blood, make interesting comparisons between the reproductive and nervous systems, and finally propose machines for exploring and investigating the underwater world. A majority of these discoveries were made in his most influential work, De Motu Animalium, meaning “On the Movement of Animals.”
Most certainly giving credit to Aristotle’s ancient work of the same name, De Motu Animalium was divided into two volumes, covering such expansive biological concepts of muscular action, physical and mathematical equations for movement, cellular structure and function, organ system functions, and finally early ideas for submarine exploration.
Before one analyzes and recognizes the influences of each of these topics in more detail, let us first analyze Aristotle’s work of the same name, and later make comparisons about Borelli’s corrections and revisions to the foundations of biomechanics. Written in approximately 350 BCE, Aristotle’s “On the Motion of Animals” approached the questions of biomechanics more philosophically and logically rather than Borelli’s later techniques of extensive mathematics, physics, and observations. Primarily, Aristotle noted that “each animal as a whole must have within itself a point at rest, whence will be the origin of that which is moved, and supporting itself upon which it will be moved both as a complete whole and in its members” (Farquhason 1). Through logic and reasoning alone, Aristotle laid the foundation for the actions of muscles later described by Borelli; effectively recognizing how muscles theoretically function.
Muscles may have only one action, one direction of movement. There is one insertion point and one origin point. Muscles act to pull the insertion towards the origin, and this process in perfect harmony throughout the body provides movement in skeletal muscles, as well as subconscious processes of cardiac and smooth muscles. Today, this knowledge is taught in any entry-level anatomy course. But imagine the academic atmospheres of 350 BCE, and later 1670 CE; times of great philosophical controversy and conflict between scholars and the Catholic Church.
Observation, logic, and research of the natural world, against the word of God, was mocked and punished in almost all societies. For many the only sanctuary for such ideas was within a text. In addition to the ideals of the scientific method and processes of observation, Borelli shared another trait with most thinkers of his time; his greatest (and most controversial) work was published posthumously. Such ideas of simple actions of muscles generating movement and life among both animals and humans challenged fundamental beliefs of life and soul; two topics most revered by the Catholic Church.
Where Aristotle struggled with logic and reasoning in scientific subjects hardly touched by higher thought, Borelli, nearly 2000 years later, struggled with a combative and antagonistic society solidified in conservative thought. Nevertheless, Borelli could not deny his observations and conclusions, many of which could not have been reached without the foundation laid out by Aristotle.
Despite Aristotle’s contributions to the topics of anatomy and biomechanics, many questions still remained. What drove the actions of muscles? What were muscles made of? How do all the muscles of an organism coordinate in such magnificent harmony? Giovanni Alfonso Borelli had these answers.
Furthering biomechanics more than any thinker up to his time, Borelli specifically described how muscular action may only contract or rest. Muscles are incapable of stretching, sliding, twisting, etc. This fundamental definition of muscular action is true today, and may stand-alone be the greatest of Borelli’s contributions. Most controversial was Borelli’s conclusion that organismal movement what derived materially; that the nervous system communicated and affected action from the muscular system (Borelli 4). Although seemingly obvious and intuitive today, this was an enormous conclusion given the society and power of the Catholic Church during the 17th century.
With his research and comparisons between human and animal muscular systems, Borelli was effectively denying a greater presence or agent which affects the movement of the natural world. Although not specifically proclaimed in De Motu Animalium, one can easily see the foundation for very secular conclusions in respect to the natural world.
With Borelli’s concepts of movement, perhaps humans and animals moved alike? Perhaps there is no immaterial cause for action, perhaps it is instead natural processes of an intricate nervous system. These are monumental positions that likely could’ve had Borelli killed by the Catholic Church.
Luckily for the scientific community, as well as all of human medicine hence, Borelli produced much of his research far from the influence of Catholicism; under the protection of Queen Christina of Sweden.
Unlike Galileo and other scientific thinkers of the time, Borelli experienced relative ease in acquiring peace and sanctuary to conduct his research, although his later life was marred by poverty and humility. Nonetheless, an environment welcome to scientific investigation and liberalism could only have assisted in Borelli’s experiences and ultimately his discoveries.
So what are the lasting effects of Giovanni Alfonso Borelli’s works? What today is shaped by his fundamental discoveries of biomechanics during the scientific revolution, nearly four centuries? Primarily, anyone who has ever undergone any form of physical therapy or orthopedic surgery has some amount of thanks to give to this most gifted and forward-thinking Italian. With his foundation of biomechanics, including how muscles coordinate with each other, human civilization has a much greater understanding and by this point mastery of treating injuries sustained to the musculoskeletal system.
It’s impossible to assume whether or not humans would have ever made these discoveries (as they likely would have) without Borelli, but that does little to discredit his monumental findings. Borelli perfectly characterizes the scientific revolution of the 17th century in that he was highly eclectic in his studies, lived by the methodologies of observation and hypothesis, and challenged the authority of the ideologically and scientifically conservative Catholic Church. It is for these reasons he exemplifies this period of thinkers much like Descartes, Galileo, and Newton.

A new philosophy of science and medicine had spread throughout 17th century Italy. Gone were the principles of the medieval scholasticism of Aquinas. Arabic cultures no longer were petitioned for their theologic interpretation of science. Magic and mysticism appealed only to the ignorant.  A shift in science had occurred. Modern 17th century scientists renounced a previously nominalistic approach. They no longer relied on abstracts and universal ideas. Instead, these contemporary scientists underscored the importance of approaching empirical experiments, mathematic concepts, and explanations only through the physical laws of nature.

The transition was the Renaissance. It was a period of intense personal and spiritual independence, which inspired an insatiable curiosity to find the physical truth. The previous premises of theoretical explanations, magical existence, and relationships between humans and astrology had eroded. The universe had a set of laws, and scientists collaborated for their methodic ascertainment. Galileo provided the telescope, da Vinci countless experiments, and Copernicus a new frame of reference; Kepler explained planetary motion, Descartes a distinction between mind and spirits, Boyle a sense of gravity to our breath, Pascal our atmosphere, and Harvey a complete circuit of blood circulation. These individuals elevated 17th century science from the obscure and irrelevant to the practical and tested.

Arguably, one of the most revolutionary and courageous scientists who surmounted this opposing conservatism in the 1600s was Giovanni Alfonso Borelli. His consummate work entitled De Motu Animalium (On the Movement of Animals)  was recently translated by Paul Maquet in 1989, thus providing valuable evidence of Borelli’s contributions to the scientific community. A physicist, astronomer, and personal medical consultant to the Queen of Sweden, Borelli documented original research regarding spinal biomechanics, muscular contraction, cardiac output, blood flow, nerve transmission, and pulmonary function, and was the first to demonstrate an effective collaboration between a physician and a biophysicist. His contributions to spinal surgeons were not insignificant. Not only did he accurately describe the anatomy of the spine, but he also calculated forces on spinal musculature and intervertebral discs, and elucidated the load-sharing characteristics of the human body. Had it not been for his steadfast and unyielding conviction, many fundamental principles of human physiology and biomechanics might have remained unexplained for years. Thus, this page is an attempt to acknowledge fully the “Father of biomechanics.”

Giovanni Alfonso Borelli’s De motu animalium
Demonstration of leg joints
Published: 1685 (Part II)

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