MATHEMATICIAN, ASTRONOMER, PHYSICIST, BIOLOGIST

Life
Son of Nicomachus and Phaestis, Aristotle is considered the most important and most methodical mind of the ancient world, and was the founder and pioneer of many fields of science. He was born 15 years after the death of Socrates, and 3 years after the founding of Plato's Academy, in Athens.

Orphaned at an early age, he was brought up by relatives at Atarnea in the Troad, where he received a good basic education. In 367 BC, at the age of 17, he went to Athens and was accepted at Plato's Academy, where he spent the next 20 years, first as a pupil and then as a teacher. He attitude towards the elderly Plato and his associates Speusippus, Xenocrates, Eudoxus and Heraclides was both critical and creative. In 347 BC - the year Plato died - Aristotle moved to Assos, where he spent the next two years and where he met his former student and colleague Theophrastus, who invited him to his own city of Lesbos. He remained there, teaching, until 343, when Philip II of Macedonia invited him to come to Pella to be the tutor of his 13-year-old son Alexander. He spent the next two years in Pella, and then moved to Stagira to continue his own work. In 338 he went to Delphi, where he studied the historical records of the oracle. He returned to Athens in 334 to teach in the "Lyceum" (a public gymnasium in the neighbourhood of the present National Garden), and spent the next 12 years in that city. He became the head of the Peripatetic school of philosophy, and worked closely with Theophrastus, who was to succeed him as its head. After Alexander's death in 323 BC, Aristotle was forced to leave Athens. He retired to his mother's property at Chalcis, where he died a few months later.

One of the craters on the moon has been named "Aristotle" in his honour.


Work
According to available sources, Aristotle is estimated to have written a total of 400 works, although only 143 of these titles are known to us today. Diogenes Laertius calculated the number of lines in Aristotle's works at "44 myriad", that is, 440,000. Some of the best-known of his works are:

"Physics"

Book I: General method on the physical sciences. Basic concepts. Analytical method. Opinions of the ancient philosophers on the first principles of nature and being. The unit, a constant and indivisible quantity. Critique of the theory of Melissus and the Eleatic school, of the physics of Plato, Empedocles and Anaxagoras. Principle of opposites. There is no "one" or "infinite". Theory of genesis. The essential and the accidental. Potential and kinetic energy.

Book II: Definition of the origin and differentiation of natural things. Difference between the mathematical and the physical. Nature as matter and form. Cause of change in matter. Two kinds of motion: natural and non-natural. Relativity of motion. Meaning of causality. Proof of the existence of the essential and the accidental. Differentiation of physics and philosophy. Distinction between nature and art. Material changes.

Book III: Preliminary theorems on the definition of motion. For there to be motion there has to be a thing. A thing is formless or informed, has property and quality and occupies space. Potential and kinetic energy. Action and reaction. Infinity. Incompatibility of infinity and space. The infinitely small and the infinitely large. Relation between the infinite and the universe. Opposition between the infinite and the concept of number and size. The concept of the infinite as a cause.

Book IV: Concept of space compared to the concept of form and matter. Opposition to the theory of Plato. Problem of existence of a thing "within itself". Proof of the error in Zeno's theory of space. Motion in relation to space. On the void. Concept of the void in relation to matter, time and motion. Time, Relation of time and motion. Time as a dimension. Continuity in time.

Book V: Types of motion. Distinction of elements of motion. The immobility of form in bodies. Action - reaction. On contact and continuity. Single motion and orbit. Conditions of absolute motion. Continuity of motion. Regular and irregular motion. Motion - inertia. Stopping or genesis of rest.

Book VI: On continuity. The line is not composed of indivisible elements (proof). Extension of the concept of continuity. Continuity of time (proof by accelerated and decelerated motion). Time - dimension. Infinite size - infinite time. Proof of the error in Zeno's theory of non-existence of motion. No continuum is indivisible. The temporal moment is indivisible. Nothing moves or is at rest at any temporal moment. Divisibility of force and divisibility of motion. Linking divisibility of force, motion, time and length. Spent force. Rest. On the transformation of state in bodies. Cyclical motion. There is no infinity of transformation.

Book VII: Everything that moves is necessarily moved by a force. Alteration of bodies as consequence of change in their state. Energy is not created or destroyed, but changes, and this change can be comprehended. Comparison of types of motion. Origin and waste of motion. Principle of autodynamic change (basis of contemporary statistics).

Book VIII: Eternalness of motion (proof). Distribution of inertia and motion in nature. Potential and kinetic energy. Cases of motion. Initial motion or transfer. Continuity of linear motion. Straight, cyclical and compound motion.

"Metaphysics"

12 books . This is Aristotle's most important work. It deals with ontology and contains a critique of the theory of numbers. The problem of substance, kind and matter. Force and energy. Creation and the principle of individuality. Motion and the four causes. Heat ("heat is motion"). There is a heaven (cosmos). Classification of numbers. Arithmetical examination of all possible forms of correlation. Multiplication. Superparticular and sub-superparticular. Ratios. Symmetrical and non-symmetrical numbers.

Aristotle's "logic" was based on analytical propositions that can be considered as mathematical formulas, capable of unlimited verification in any substitution of formal elements.

"De Caelo"

4 books. Exposition of astronomical theories. The cosmos as a whole is spherical, with the spherical earth at its centre. Aristotle assumed that the distance between the Pillars of Hercules (Straits of Gibraltar) and the Indies (via the Atlantic Ocean) was not great: this encouraged Columbus to undertake his journey. Length of the perimeter of the terrestrial globe ("forty myriad stades", or 73000 kilometres, nearly double the actual measurement). Description of the universe. Planets: Moon, Sun, Mercury, Venus, Mars, Jupiter and Saturn. Fixed stars. Celestial sphere (containing a second concentric sphere). Movement of the celestial bodies. Aristotle accepts a single cosmic system. On momentum (mass times acceleration of a body is constant).

"De Generatione et Corruptione"

3 books. Theory of chemical transformations.

"Meteorologica"

4 Books .

Book I: "On the planets".

Book II: "On comets".

Book III: "On meteors".

Book IV: "On metals and minerals".

"Historia animalium"

10 books. Comparative anatomy, physiology and general biology.

"De Partibus Animalium"

4 books. General introduction to biology. Rejection of the classification of Speusippus. Study of the construction of the organs of different animals on the basis of their anatomies and explanation of their construction on the basis of his theory of "entelechy". Book IV deals with embryology.

"De Incessu Animalium"

1 book. Considers the question of local motion and studies the motor organs of animals.

"De Incessu Animalium"

1 book. Complementary treatise to the above.

"De Generatione Animalium"

5 books. Treats the problem of the reproduction of organisms, their reproductive organs, birth and heredity.

"On Plants

2 books. Only two fragments survive (in Nicholas of Damascus). Completes the work of Democritus, comparing all known forms of plants and animals. Proposes the existence of indiscernible transitions between all organisms, from the smallest particle to man. Nature is an organic whole and creatures constantly change and develop into higher forms. Aristotle had access to a wealth of botanical material, not only from Greece but from Asia as well, sent to him by his former pupil Alexander. He founded the first botanical gardens in Athens, near the Ilisos River, and appointed his old friend and former pupil Theophrastus as its director. This institution also provided practical teaching, according to Diogenes Laertius.

"Politics"

8 books. General theory of forms of government. Discusses among other things the general principles of urban planning. Creation of cities. Purpose of cities. Social constitution of the state. Outline of the organisation of the ideal state. Children and music in cities. Aristotle's model was applied in the selection of space when the settlement of Cassope was founded, while the street lay-out, with its intersecting grid pattern, followed the Hippodamian system.

"Problems"

Discusses problems belonging to different branches of science. Reflection of sound. Reflection of light. Electrically produced voids. Levers. Parallelogram of speeds. Compound forces.