How we cite our quotes: (Name of Play, Act #)
Quote #1
MINNIE: My, she's awful handsome ain't she?
LOUISA: Too furrin' lookin' for my taste.
MINNIE: Ayeh. There somethin' queer lookin' about her face.
AMES: Secret lookin'—'s if it was a mask she put on. That's the Mannon look. They all has it. They grow it on their wives. Seth's growed it, too, didn't you notice—from being with 'em all his life. They don't want folks to guess their secrets. (Homecoming, Act 1)
Back in the day, actors in ancient Greece would appear on stage wearing masks that hid their faces. With these descriptions of the Mannon mask-face, O'Neill is bringing back the mask, but not just as a shout-out to the Greek playwrights. It sets the stage for the general patterns of deception we see in the Mannon relationships. He tells us right away that things are not what they seem.
Quote #2
LAVINIA: We've so much to tell you. All about Captain Brant.
MANNON: Vinnie wrote me you'd had company. I never heard of him. What business had he here?
CHRISTINE: You had better ask Vinnie! He's her latest beau! She even went walking in the moonlight with him.
LAVINIA: Oh!
MANNON: I notice you didn't mention that in your letter, young lady!
LAVINIA: I only went walking once with him—and that was before—
MANNON: Before what?
LAVINIA: Before I knew he's the kind who chases after everything he sees.
MANNON: A fine guest to receive in my absence!
LAVINIA: I believe he even thought Mother was flirting with him. That's why I felt it my duty to write you. You know how folks in town gossip, father. […] (Homecoming, Act 3)
Lies are flying left and right in this little exchange, and everybody's got their motives for why they're peddling the BS. There are a million things going on that Ezra doesn't know about in this scene. It's like a ping-pong match between Christine and Lavinia to see who can spin the narrative most effectively to keep Ezra in the dark.
Quote #3
CHRISTINE: […] You want the truth? You've guessed it! You've used me, you've given me children, but I've never once been yours! I never could be! And whose fault is it? I loved you when I married you! I wanted to give myself! But you made me so I couldn't give! You filled me with disgust.
MANNON: You say that to me! No! Be quiet! We mustn't fight! I mustn't lose my temper! It might bring on—!
CHRISTINE: Oh, no! You needn't adopt that pitiful tone! You wanted the truth and you're going to hear it!
MANNON: Be quiet, Christine!
CHRISTINE: I've lied about everything! I lied about Captain Brant! He is Marie Brantôme's son! And it was I he came to see, not Vinnie. I made him come! (Homecoming, Act 4)
There you have it. Lie until you can use the truth to whack somebody over and over again like a human piñata. The message is that this is what happens when you've been lying during your whole marriage; eventually the truth comes bursting out in a destructive way. Christine's "confession" helps create a whole lot of tension that makes the finale to Homecoming—Ezra' death—all the more powerful.