Diogenes the cynic, Diogenes ho Sinopeus, attacked corruption was povertized and even sold into slavery. His teachings and beliefs were used and taught by many others with one forming school of stoicism. None of his writings survived and this would most likely be because the corrupt didn't want anyone to read and learn truth trying to hide what huge pieces of crap they were and the evil they worked.

(Sinoplu Diyojen) Diogenes of Sinope. Spent his days searching Athens for an honest man.

Jean-Léon Gérôme - Diogenes - Walters 37131 - Diogenes of Sinope - Wikipedia, the free encyclopedia

Diogenes: 1860 by Jean-Leon Gerome (Walters Art Gallery, Baltimore, United States) - Academic Classicism

Diogenes of Sinope was one of the Greek founders of Cynic philosophy. He died at Corinth in 323 BCE. During his life, Diogenes of Sinope was a controversial figure.

He became notorious for his philosophical stunts such as carrying a lamp in the daytime, claiming to be looking for an honest man

Waterhouse-Diogenes - John William Waterhouse - Wikipedia, the free encyclopedia

John William Waterhouse (1840-1917)

Diogenes by John William Waterhouse, 1882 Diogenes inured himself to the weather by living in a clay wine jar belonging to the temple of Cybele.

Diogenes of Sinope was one crazy dude.

An century CE painting showing Diogenes of Sinope looking for an honest man (Johann Heinrich Wilhelm Tischbein - Nagel Auktionen)

Diogenes - John William Waterhouse

When Lightning Struck!: The Story of Martin Luther by Danika Cooley

Diogenes of Sinope

Zanchi: Diogenes seeking a man of integrity - with lamp and attendant owl (symbol of Pallas Athene).