Eleatic philosopher who held being to be one, immobile and finite.
Aristotle disproved the argument of Parmenides in the Physics.
The argument of Parmenides says that whatever is other than being is non-being. What is non-being is nothing. Whatever is other than being, is therefore, nothing. Being, also, is one. Whatever is other than this one is nothing and there is only one being.
Parmenides also concluded that this being would be immobile. There is nothing by which is would be moved. There is nothing outside of it by which it would be moved.
Parmenides considered being under the aspect of being. He held it to be one and finite.
(NB: Indeed, being is not infinite, however, takes the shape of a perfect sphere for Parmenides, a single point that extends out a path in all directions, making a sphere...)
Aristotle answers the argument of Parmenides on the basis that he built his argument under false propositions. He also did not draw his conclusions correctly. Parmenides assumed false propositions. He held that “What is” i. e. Being, is only used simply or in one way. In fact, it is used in several ways: one way for substance and another way for accident. Insofar as it is used for accident, it is used in many ways according to different genera. Being can also be used commonly for substance and accident.
From St. Thomas Aquinas's commentary on Aristotle's Physics.
(Book I, Lecture 6, n37)
On Nature
Parmenides's sole work was known as 'On Nature' and it only survives in fragments. 160 of probably about 800 verses survive. The work has 3 parts:
A proem, or introduction, an allegorical narrative explaining the purpose of the work. The proem describes the journey of the narrator who seeks a revelation on the nature of reality from an unnamed goddess. The narrative includes a lot of allegorical symbols. There is a speeding chariot with glowing axels. There are also those maidens who are "duaghters of the Sun" who move the narrator to a strange destination, outside of our human paths. These allegories have given rise to a variety of interpretations, including comparisions to Homer or Hesiod. However, there is little scholarly consensus on any real interpretation of these allegories. It may be impossible, to, based on the fragments to determine the real meaning of the allegories.
The Way of Truth: about 90% of which probably survives. Parmenides distinguishes between the unity of nature and its variety. Parmenides insists on the reality of unity and the illusoriness of variety in being. Variety is the object, not of truth, but of opinion. The next section, will discuss which is illusory.
The Way of Opinion: far longer but less better preserved section of the poem. Deals with cosmology and even perhaps indicates a spherical nature to the planet Earth.