In existographies, Celsus (c.125-180AD) (SHP:18) was a Greco-Roman philosopher, characterized as a dabbler in various schools of thought, including Platonism and Stoicism (Hoffmann, 1987), and Epicureanism (Origen, c.230), and a student of the history and religious customs of many nations, noted for [1]

Overview
In c.175AD, Celsus published Reason of Truth: The True Word (Λόγος Ἀληθής, Logos Alēthēs), various translated as The True Word (Ѻ) or The True Doctrine (Hoffmann, 1987), wherein he attempted to refute the validity of the newly forming sect of Christianity. [3]

In c.230AD, Origen, in his Against Celsus (Contra Celsum), an apologetic treatise, argued against the ideas set forth by Celsus, and in which he quotes extensively from Celsus’ The True Doctrine.

Quotes | On
The following are quotes on Celsus:

“Celsus appears to have been to the second century what Voltaire was to the eighteenth.”
— DeRobigne Bennett (1876), The World’s Leading Sages [2]

Quotes | By
The following are quotes by Celsus:

“You may see weavers, tailors, fullers, and the most illiterate and rustic fellows, who dare not speak a word before wise men, when they can get a company of children and silly women together, set up to teach strange paradoxes among them. This is one of their [Christian] rules: Let no man that is learned, wise, or prudent come among us: but if they be unlearned, or a child, or an idiot, let him freely come. So they openly declare that none but the ignorant, and those devoid of understanding, slaves, women, and children, are fit disciples for the god they worship.”
— Celsus (c.175AD), The True Word; cited by Origen (c.230AD); cited by DeRobigne Bennett (1876) in The World’s Leading Sages (1876) [1]

See also
● Anders Celsius (1701-1744) | eponym of the Celsius scale

References
1. (a) Celsus, Aulus. (c.45AD), Publication (Ѻ). Publisher.
(b) Bennett, DeRobigne (1876). The World’s Sages, Thinkers and Reformers: Biographical Sketches of Leading Philosophers, Teachers, Skeptics, etc. (Celsus, pg. 291). Truth Seeker Company.
2. Bennett, DeRobigne (1876). The World’s Sages, Thinkers and Reformers: Biographical Sketches of Leading Philosophers, Teachers, Skeptics, etc. (§: Celsus, pgs. 288-; quote, pg. 291). Truth Seeker Company.
3. Celsus. (c.170AD). The True Doctrine (translator: R. Joseph Hoffmann) (abs). Oxford University Press, 1987.

External links
● Celsus – Wikipedia.
● The True Word – Wikipedia.