Geocentric model and planets were holes in invisible wheels surrounding Earth; through the holes, humans could see concealed fire. About the same time, Pythagoras thought that the Earth was a sphere (in accordance with observations of eclipses), but not at the center; they believed that it was in motion around an unseen fire. Later these views were combined, so most educated Greeks from the 4th century BC on thought that the Earth was a sphere at the center of the universe. In the 4th century BC, two influential Greek philosophers, Plato and his student Aristotle, wrote works based on the geocentric model.
Singular term pronouns (e.g. "she"), demonstrative pronouns (e.g. "this"), etc. Historically, various definitions for "singular term" have been offered: Singular term A singular term is a paradigmatic referring device in a language. Singular terms are of philosophical importance for philosophers of language, because they "refer" to things in the world, and the ability of words to refer calls for scrutiny. Singular terms are defined as expressions that purport to denote or designate particular individual people, places, or other objects. They contrast with "general terms" (such as "car" or "chair") which can apply to more than one thing. There are various kinds of