jan 5, 384 BC - Aristotle
Aristotle (384–322 BC) was Plato's prize student and "the mind of the school". Aristotle observed "there are stars seen in Egypt and [...] Cyprus which are not seen in the northerly regions." Since this could only happen on a curved surface, he too believed Earth was a sphere "of no great size, for otherwise the effect of so slight a change of place would not be quickly apparent." (De caelo, 298a2–10)
Aristotle provided physical and observational arguments supporting the idea of a spherical Earth:
Every portion of the Earth tends toward the centre until by compression and convergence they form a sphere. (De caelo, 297a9–21)
Travelers going south see southern constellations rise higher above the horizon; and
The shadow of Earth on the Moon during a lunar eclipse is round. (De caelo, 297b31–298a10).
The concepts of symmetry, equilibrium and cyclic repetition permeated Aristotle's work. In his Meteorology he divided the world into five climatic zones: two temperate areas separated by a torrid zone near the equator, and two cold inhospitable regions, "one near our upper or northern pole and the other near the ... southern pole," both impenetrable and girdled with ice (Meteorologica, 362a31–35). Although no humans could survive in the frigid zones, inhabitants in the southern temperate regions could exist.
Aristotle proposed a fifth element, aether, in addition to the four proposed earlier by Empedocles.
Earth, which is cold and dry; this corresponds to the modern idea of a solid.
Water, which is cold and wet; this corresponds to the modern idea of a liquid.
Air, which is hot and wet; this corresponds to the modern idea of a gas.
Fire, which is hot and dry; this corresponds to the modern ideas of plasma and heat.
Aether, which is the divine substance that makes up the heavenly spheres and heavenly bodies (stars and planets).
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Life Through My Eyes in Time.
Trying to understand life around me in the times of now and ...