PosidoniusIn existographies, Posidonius (135-51BC) (IQ:170|#276) (CR:13) was a Greek scientist, historian, philosopher, astronomer, and general polymath, characterized the “greatest polymath of antiquity” (Dodds, 1973) (Ѻ) and a scholar of “almost Aristotelian stature” (Walsh, 1998), noted for []

Stoicism
Posidonius was a pupil of Panaetius (185-109BC) (Ѻ), the fourth head of the Stoic school, from 129 to 109BC, who was a strong admirer of Plato and Aristotle, who built bridges with the Peripatetics. Posidonius became the chief philosopher through which Cicero learned Stoicism. [1]

Astronomy
Posidonius advanced the theory that the sun emanated a vital force which permeated the world.

In 90BC, he estimated the distance to the sun to be 9,893 times the earth’s radius, i.e. he calculated distance to sun to be 39M miles (actual: 93M miles); an improvement over measurements by Aristarchus. (Ѻ)

Posidonius constructed an orrery, possibly similar to the Antikythera mechanism (Ѻ), which, according to Cicero, exhibited the diurnal motions of the sun, moon, and the five known planets.

Sympathy | Proto-chemistry
In c.70BC, Posidonius advocated a theory of cosmic "sympathy" (συμπάθεια, sumpatheia), the organic interrelation of all appearances in the world, from the sky to the earth, as part of a rational design uniting humanity and all things in the universe, even those that were temporally and spatially separate. (Ѻ)

In 2008, Ernesto Paparazzo, in his “Why Take Chemistry Stoically?”, argued that some of the ideology of Posidonius’ logic, e.g. his “generation and destruction”, form a sort of proto-science of chemistry, as being forerunners to chemical elements, chemical species, nuclear reactions, conservation of mass, and chemical change at solid surfaces; the following is a representative quote: [1]

“Posidonius says that there are four kinds of destruction and generation that occur from what is to what is. For they [i.e. the Stoics] rejected as unreal any destruction from or generation into what is not...Of change into what is, he distinguishes: (a) dismemberment [diairesis]; (b) transmutation [alloiôsis]; (c) fusion [sugkhusis]; (d) breaking up of a whole, called dissolution [analusis]. Of these four, transmutation is related to substance (ousia); the other three have reference to qualities supervening on substance. Generation is analogous to that. Substance does not admit of increase or diminution by addition or subtraction, but only of transmutation, like number and measure. But individually qualified particulars like Dion and Theon [two stock names in Stoic logic (Kidd 1988a, p. 385)], also admit of increase and diminution. This is also why the predominant quality of each thing persists from generation to destruction, as in the case of animals, plants and things like them which admit destruction. In individually qualified particulars, he says, there are two receptive parts, in respect to the reality of substance and of quality. It is the latter, as we have often kept saying, that admits of increase and diminution. The individually qualified particular is not the same as its constituent substance, nor is it different either; but is all but the same in that its substance is a part of it and occupies the same space. For things that are said to be different from others must both be spatially separate and not viewed as part and whole.”
— Ian Kidd (1972), Posidonius: Volume Three, The Translation of the Fragments [2]

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Soul
Posidonius outlined a “moral psychology” that acknowledged some type of non-rational forces in the soul analogous to aspects of Platonic ideas. (Ѻ)

References
1. Cicero. (45BC). The Nature of the Gods (Introduction, translation, and notes: Patrick Walsh) (Stoa Poikile, pg. xxxiii). Oxford University Press, 1998.
2. (a) Kidd, Ian G. (1972). Posidonius: Volume Three, The Translation of the Fragments (pgs. 156-57) (Ѻ). Cambridge University Press, 1999.
(b) Paparazzo, Ernesto. (2008). “Why Take Chemistry Stoically? The Case of Posidonius” (abs), Foundations of Chemistry, 10(1):63-75.

External links
● Posidonius – Wikipedia.

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