This was a pretty nostalgic group. It's hard not to be nostalgic when it comes to philology: who the heck cares about—much less studies—philology these days? When was the last time sometime told you his or her major was philology? Have you seen a Philology section at Barnes and Noble? Hint: it's not at the front.
Philology reached its peak right around World War II, so this group would get together and talk about the beauties of close textual readings, the magic of words, and the unnerving information you could find out about life in the Middle Ages if you paid enough attention to what you were reading.
Ernst offered true leadership for P.U. because he was truly committed to understanding how personal details reveal historical truths. In other words, he thought a character's runny nose might indicate that there was a lethal epidemic of tuberculosis at the time the novel was written. Or that a beautiful damsel's almost-indiscernible blemish was the beginning of smallpox. You get the point. Ernst always brought in one of his favorite Greek texts and gave it a good parsing.
Just because Roman was a linguist didn't mean he couldn't hang with the philologists. Talk about detail-oriented: this guy could talk about syntax until he was blue in the face, and he was just getting started. He and Auerbach shared an interest in universal qualities—it's just that Jakobson was interested in language, while Auerbach was interested in human experiences.
Wellek was a linguist, too, so sometimes things would get a little heated between philologists and linguists in this group. Wellek was always good at getting things to simmer down when linguists started accusing philologists of not being rigorous and precise enough. Which, frankly, happened pretty often.