Our Gemara quotes a baraita that attributes the prohibition against raising pigs to the following story. After the death of Shlomzion haMalka who bequeathed her kingdom to her son Hyrcanus, his brother Aristoblus contested the decision and succeeded in ousting his elder brother. With the encouragement of Herod’s father, Antipater, Hyrcanus gathered an army and attacked the city, forcing Aristoblus and his supporters to barricade themselves in Jerusalem. During this siege, which took place in 65 BCE, the Jews inside the city offered to purchase animals for daily sacrifices in the Temple in exchange for large sums of money.
The baraita relates that someone who was there who was knowledgeable in Greek wisdom hinted to the men outside the city that it was only the Temple service that kept Jerusalem from falling. The next day, in exchange for the coins that were sent down, instead of the promised sacrifice the soldiers sent back a pig, which reached out with its hooves halfway up the wall and caused the ground to shake. At that point the sages established an enactment forbidding the raising of pigs in Israel and teaching Greek wisdom to children.
This story appears in Josephus (Antiquities of the Jews 14:2), where it is related that the Jews inside the city offered 1000 drachmas for every Pesaḥ sacrifice. The consequence of the story according to Josephus was a storm that destroyed almost all of the harvest in the land of Israel. Perhaps this incident is what the baraita means when it says that “the earth shook.”
Hokhma yevanit – Greek wisdom -does not appear to be secular knowledge generally, but rather refers to knowledge of Greek culture, music, literature, etc. Few people spoke classical Greek, and the story in our Gemara may indicate that the man “knowledgeable in Greek wisdom” was able to hint his intentions to others by presenting his message in a manner that only a select few could understand.