题干分析：讲座主旨。

原文定位：

So in the third century BCE, there were several schools of philosophy flourishing in Greece. Now by school, I'm referring to a set of philosophical teachings that gained a group of followers. I'd like to talk a little bit about one of the most popular of these schools, Epicureanism, which was founded by the philosopher Epicurus.

选项分析：教授首先提到公元前3世纪在希腊有很多兴盛的学派，而这次主要就讲其中一个非常著名的学派伊比鸠鲁学派，随后主要都在讲伊比鸠鲁学派的内容、对现代社会的影响等，可知应选C选项。A、D选项未提及；B选项仅是介绍伊比鸠鲁学派内容的一小部分。