Who says the following and why? "You see, we're all savages, more or less. We're supposed to be civilized and cultured—to know all about poetry and philosophy and art and science, and so on; but how many of us know even the meanings of these names? [To Miss Hill] What do you know of poetry? [To Mrs. Hill] What do you know of science? [Indicating Freddy] What does he know of art or science or anything else? What the devil do you imagine I know of philosophy?"

1) Liza is mildly embarrassing herself in her meeting with Mrs. Higgins and the Hills.
2) Mrs. Higgins is trying to reel the conversation in after Higgins has worked everybody up.
3) Higgins is explaining why saying what one really feels is a very bad idea.
4) Higgins has become infuriated at Freddy and is taking it out on the whole party.