Professor Ericson: Very well, Mr. Cooper, how do you know you're not just dreaming butterflies can't dream?
Sheldon: Because I'm awake.
Professor Ericson: Or are you dreaming you're awake?
Sheldon: You can see I'm awake and you can hear me talking.
Professor Ericson: Yeah... I don't know. I saw some pretty trippy stuff at a Grateful Dead concert. The drummer turned into a tap-dancing walrus and floated away. So we can't really trust our senses, can we?
Sheldon: We can validate them by comparing them with other observers.
Professor Ericson: Mm, but that would mean we have to hear what they say, which requires... trusting our senses. Do you see a problem with your argument, Mr. Cooper?
Sheldon: I could concentrate better if you weren't flashing your toes at me.

Principal Petersen: Our next young speaker needs no introduction, but that didn't stop him from writing one and making me read it. [laughter] "Fun fact." [audience groans, murmurs] I hear you. "The word 'valedictorian' is from the Latin 'valedicere,' meaning 'to say farewell.' It is primarily used in the United States, Canada, the Philippines and Armenia." Maybe that fact's more fun in Armenia. Please welcome your valedictorian, Sheldon Cooper.
Mary: Yay, Shelly!
Sheldon: Hello. I'm not very comfortable speaking in front of crowds. But there's a technique to reduce stage fright by focusing on one person in the audience and delivering your speech just to them. That's what I'll be doing today. If it weren't for this person, I wouldn't be here right now. They've taught me a lot, and it's by their example that I found the courage to move forward into this new and exciting chapter of my life. Missy... ...this is for you. Change can be scary, but I know we're going to be fine... ...because like you said, "It's okay to be scared. We just have to do it anyway." So if any of my fellow graduates are nervous about the future, know that you're not alone. I suggest you all try to be as brave as my twin sister. That's my plan. Missy, I wish I could give you advice about middle school, but I was so smart, I skipped it. If you make it to high school, we'll talk. Thank you. [applause]

Mary: Sheldon, faith means believing in something you can't know for sure is real. And right now, I am struggling with that.
Sheldon: So you don't believe in God anymore?
Mary: That isn't something for you to worry about. I need to figure this out myself.
Sheldon: Can I help? Maybe I could provide a fresh perspective.
Mary: I don't think so, baby.
Sheldon: Did you know that if gravity were slightly more powerful, the universe would collapse into a ball?
Mary: I did not.
Sheldon: Also, if gravity were slightly less powerful, the universe would fly apart and there would be no stars or planets.
Mary: Where you going with this, Sheldon?
Sheldon: It's just that gravity is precisely as strong as it needs to be. And if the ratio of the electromagnetic force to the strong force wasn't one percent, life wouldn't exist. What are the odds that would happen all by itself?
Mary: Why are you trying to convince me to believe in God? You don't believe in God.
Sheldon: I don't, but the precision of the universe at least makes it logical to conclude there's a creator.
Mary: Baby, I appreciate what you're trying to do, but logic is here. And my problem is here.
Sheldon: Well, there are 5 billion people on this planet and you're the perfect mom for me. What are the odds of that?

Missy: What's it like to not believe in God?
Sheldon: It's great. Big fan.
Missy: Are you ever afraid you're wrong?
Sheldon: About religion? Never. About other things? Also never.

Sheldon: I stopped at the library today and picked up books on epistemology, Descartes's dream argument and the foundations of scientific logic. Do you know what she's going to do?
Meemaw: Rue the day?
Sheldon: The day, the night. If it's rue-able, she's going to rue it.

Missy: And at lunch, an eighth-grade boy said, and I quote, "I like Funyuns, too."
Mary: Wow.
Missy: I know.

Mary: Hey, Brenda.
Brenda Sparks: She didn't want you to walk her in?
Mary: No. How about Billy?
Brenda Sparks: Oh, I walked him in. Found his homeroom. Explained that "homeroom" is different than his room at home. Still not sure he gets it.
Mary: Tough day.
Brenda Sparks: Yeah.
Mary: You want to get some coffee?
Brenda Sparks: I was thinking vodka, but coffee will do.