« ... Isaac Newton was born on 4 January 1643. He studied at Trinity College - Cambridge. His teacher of mathematics, Isaac Barrow (1630-1677), author of "Lectiones mathematicae", aware of his pupil’s talent, encouraged him to continue his studies, through which he was already able to understand the "method of fluxions", otherwise called "infinitesimal calculus", which he used to solve some problems of analytic geometry. 

During the years of the Great Plague he left Cambridge and for some time he lived in the mid of the country, at Woolsthorpe, in his small stone built house (1665-1666). This period was quite fruitful. During this time, he suddenly grasped the theory of gravitation. Famous is the incident, reported by his niece, who said such thought came into his mind after an apple had fallen onto his head, while he was resting under a tree. He studied optics, and developed such studies on his return to Cambridge, where he built a reflecting telescope, that improved Galileo’s telescope. 

He was elected Professor of Mathematics in 1669, succeeding to his master (Isaac Barrow), who, instead, took up the Chair of Theology. He analyzed the white light and decomposed it by means of a prism. Making use of an "experimentum crucis" (crucial / critical experiment), he presented this work to the Royal Society, becoming, at the same time, a member of it.

In such an occasion, for the first time, Newton expounded his theory on the corpuscular nature of light, according to which the emission of particles, different in size, could explain a number of luminous events. 

For this idea, he was criticised by some philosophers who conceived this theory a new philosophical opinion, while Newton argued it was only a hypothesis originating from experiments fit to prove facts. His reaction - he never changed his character even when time passed by - made him reluctant to publish the results of his studies. He published them in 1704, years after his first intuition. Similarly, the results of his gravitational theory were published late. He proved such theory was scientifically sound using Jean Picard’s results (1620-1682) on measurements of the Earth’s dimension. 

His interest for alchemy was tied to the years of his youth. During this period, he purchased a number of instruments, suggested by Lazarus Zetner’s work: "Theatrum chemicum", all suitable for these studies. 

In January 1684 a conversation took place among Halley, Wren and Hooke. Newton also became involved in it. It was followed by the publication: Philosophiae Naturalis Principia Matematica (Mathematical Principles of Natural Philosophy). 

In this very important work he explained Kepler’s theory on the hypothesis of Copernicus, assuming that a gravitation towards the center of the Sun decreases in accordance to the inverse of the squares of the distances and is proportional to the quantity of solid material of the planets. 

This work harmonized all former theories putting together Copernicus, Descartes, Kepler and Galileo as if they were one, explaining the great book of nature. Starting from a corpuscular vision of reality, Newton used mathematics to understand its structure. 

With three laws, the three laws of motion, Newton explained the structure of the universe and introduced the concepts of absolute time and space, allowing to better define the status of rest and of motion. 

These laws were much criticized, as they were not empirically verifiable. Anyway, it was inside the absolute space, that Newton said was the whole of the celestial bodies withheld by a centripetal force (gravity). 

In Book III of the Principia, Newton expounded the law of gravity, explaining the tie that binds the Moon to the Earth and the Earth to the Sun. Additionally he explained the tidal process. 

Through gravity Newton explained the motion of the planets; of the comets; of all the other astral bodies and that of the Earth’s precession. 

The elliptical motion of the celestial bodies was made explicit and proved by a force that compelled them to cut down the strait line they would have traced by inertia. It was possible to affirm, that it was through these assertions, that the myth of the circular motion became fully anachronistic. A motion, that up to Newton, all researchers had to take into consideration and to deal with. 

In 1689 Newton became a Member of the Parliament of England, for Cambridge University. During this year he made friends with John Locke. 

In 1692 Newton published his first notations on infinitesimal calculus, but, at the same time he continued to devote a great deal of his time to alchemy. Much of his work and his laboratory went destroyed in a fire. This event caused him a nervous break-down. It took him a long time to recover. Maybe he never fully recovered. 

From 1696 onward Newton became a public figure: he was appointed Warden of the Royal Mint and in 1699 he was promoted to Master of the Mint. In 1703 he was elected President of the Royal Society. He published "Opticks" (1704) and the second edition of the "Principia". 

His algebra lectures are dated 1707 (Arithmetica Universalis). Those on optics (Lectiones Opticae) were published posthumously in 1729. 

In 1727 coming back from London, where he had taken the chair at a meeting of the Royal Society, he started to feel unwell. He rapidly became worse and died in his house at Kensington on 20 March 1727. He was buried in Westminster Abbey, with much pomp. Voltaire, among many others, attended the funeral. 

During the course of his life, Newton’s intellectual work was extensive and complete. His interest for nature, though precise and specific, did not disregard to take into account theological and philosophical considerations, basis and spur for his desire of research. 

The teachings of Descartes had been deeply assimilated, leaving an inheritance, that Newton not only made his, but even developed. 

His lucid reasoning was tangible in the clearness of his procedure, that set forth his method based on four rules, quoted in Book III of the Principia, explaining how he wanted to carry out the research and in what it consisted. Such methodological rules showed metaphysical assumptions on nature and, consequently, also on the universe. 

The first rule, once again, took up Kepler’s idea of nature, a simple construction where nothing was in vain, or, even less, was complicated.(84). 

The second rule presented the axiom of nature’s uniformity, according to which, to natural effects of the same kind, the same causes should be assigned, as far as possible. (85). 

The third rule, once again, underlined the concept that reality was naturally uniform when the qualities of bodies were considered. If they did not suffer intensification and remission and pertained to all bodies upon which experiments could be carried out, such qualities ought to be taken as qualities of bodies universally. (86). 

Newton expounded the corpuscular theory of bodies. He said every object was formed by particles on which it was impossible to say anything except that they existed. However an immediate question arose on their nature and on the possibility that they could be further divided. Newton argued our minds were capable to conceive even smaller parts, as in mathematics, but that it was not possible for us to distinguish if they could be divided, "by means of nature’s power". Following the concept of uniformity, if a single experiment proved possible that a particle, whatever, could be divided, infinite divisibility of the particles would become the rule. 

Newton stopped in front of the limitations that were peculiar to senses and of the impossibility that verification could be certain. He only accepted nature was simple and consonant with herself. 

In the fourth rule he expounded that in experimental philosophy propositions gathered from the phenomena by induction were to be taken as true, whether exactly or approximately, least they became nullified by hypotheses (87). 

At the end of the Principia, Newton expounded the General Scholium, where the origin of this world, simply ordered and traceable by induction was explained as the achievement of a Supreme One’s design, a Divine Intelligence, as the order of the stars in the sky 
prove (88). 

Newton in the General Scholium, at the end of Book III, wrote: "Hitherto, I have set forth the phenomena of the Heavens and of our sea through the force of gravity, but I have not yet assigned the cause of gravity. This force does indeed arise from some cause which penetrates all the way to the centers of the Sun and the planets, with no diminution of power". 

The existence of such force [gravity] was testified through observation, but Newton admitted he did not know either the cause nor the essence, as he was not yet able to deduce the reasons for these properties of gravity from the phenomena, so he did not contrive hypotheses. 

With the expression "hypotheses non fingo", that means "I do not contrive hypotheses", Newton set up a method, that took into consideration only the results which were tangible and achievable through observation. This reason allowed Newton to support the reliability of his theory on gravity, though he was not able to prove its origin (89). 

It is surprising that he opened a diatribe with those philosophers that interpreted his studies on light, as simple theoretical hypotheses. As a result, he delayed forty years before publishing his studies. He built his system on the ontological axiom stating nature was simple, ordinate and uniform. Nevertheless, all this work was systematically based on the rules he established and results, initial axioms apart, were exclusively derived from a sensitive investigation. 

He asserted physical and metaphysical hypotheses had no place in experimental philosophy: as such, Newton entirely rejected them. 

Finally the dream of Peter Ramus (Pierre de la Ramée) came true. In vain Ramus discussed with Tycho Brahe on the need for experimental philosophy. Brahe was too much far away from such reasoning and was not prepared to accept it. 

Control on the hypotheses was a "sine qua non" that allowed to read and understand nature. All the bodies were formed by particles, regulated by the laws of gravity and dynamics. These were also the basis of Kepler’s laws. 

Gravitation was a force, an independent cause, that passed even through the empty space. The empty space was a static space. A space where no objects were present. This concept resumed the concept of vacuum of the ancient naturalistic philosophers, of the pre-Socratics and of Plato: they assumed space was a container, in which there was nothing except invisible air. In the Euclidean geometry space was immutable and independent from any noticeable movement. Only Einstein, by raising a doubt on the validity of such theory, improved the cosmic perspective with his Theory of Relativity. 

In 1669, Newton also gave his contribution to mathematics, publishing the treatise "Methodus fluxorum et seriorum infinitarum" (Method of fluxions and of infinite series), a study on infinitesimal calculus, that involved him in a dispute with Leibniz, who reached the same conclusions through a different way. Leibniz was accused of plagiarism.

A year after, Newton expounded a new theory through which he explained some optical phenomena mechanically, assuming they were influenced and determined by the space occupied by the ether . The variation of its density caused the corpuscles of the light, suspended in it, to change direction. By means of this subtle matter, he was able to explain refraction, reflection and inflexion (or diffraction), and even Newton’s rings. 

Around 1674 Newton became convinced ether did not exist – he definitively abandoned this concept -, and replaced it with ideas of attraction – repulsion between particles. 

Contributions Newton offered to Science were really numerous. Each discovery was a step forward. Mathematics were mostly important, as all his studies were based on this discipline. His studies on lenses, light and optical instruments improved observation techniques and gave strength to his assertions. 

Newton was a man of his time (XVII century), but already a scientist. Trying to find, through experiments, a valid law, universally accepted, he granted humanity the consciousness of nature.

He was not able to separate his religious beliefs and his trust in a world set up in accordance with a philosophy rooted far back into the past from pure scientific research work, the starting point to reach those results that were used later on . 

A scientist therefore, but also a man, highly religious and a philosopher ... » 
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