Protagoras was born in 490 BCE in Abdera, Thrace. He was to become a pre-Socratic philosopher, writer, and sophist, which meant that he taught others Greek rhetoric and fallacious arguments. There are three claims that he is famously known for: (1) that man is the measure of all things, (2) that he could make the "weaker argument appear stronger," and (3) that there was no proof of theistic views, and he could not tell if the gods existed or not. His first claim was – and still is – viewed as a radical form of relativism, meaning that in his statement he implies that all beliefs and belief systems are equally valid. Impiety was a crime punishable by expulsion in fifth century Greece, and Protagoras' agnostic views on religion – as can be inferred by his third claim – eventually led to his trial in Athens, where he was expelled. After his banishing, Protagoras spent his life in exile, and eventually he died in 420 BCE while still being cast out.
Cause of Event.
Protagoras was a sophist, and a controversial philosopher. He expressed his agnostic point of view in his writings, which not many people accepted at the time. Because sophistic skills promoted injustice in court and in ethics, the term "sophist" acquired a negative connotation. Because of many of his controversial works, Protagoras was ridiculed and was viewednegatively by the public. This negativity and widespread hatred of his religious impiety is what caused his banishing, and his books "On the Gods" and "Truth" were the straws that broke the camel's back.
Book Burning.
Although it was not uncommon for blasphemous or heretical scripture to be publicly burned in ancient Greece, the burning of On the Gods was the first recorded to occur. But the tremendous effect of the burning of Protagoras' book was unlike any other book burning at the time. In his book, he wrote "Concerning the gods, I have no means of knowing whether they exist or not, nor of what sort they may be, because of the obscurity of the subject, and the brevity of human life.