The dark cave symbolically suggests the contemporary world of ignorance and the chained people symbolize ignorant people in this ignorant world. The raised wall symbolizes the limitation of our thinking and the shadow symbolically suggest the world of sensory perception which Plato considers an illusion.
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The "Rosetta Stone" — which was discovered in mid-July 1799 during construction of a fort by a French military expedition at the town of Rashid (ancient Rosetta) — contains text written in Egyptian hieroglyphs, Demotic (a written script used by the Egyptians between the seventh century B.C. and the fifth century) and ancient Greek.