Sheldon: We have a problem.
Dr. John Sturgis: What?
Sheldon: Zero might not exist.
Dr. John Sturgis: [chuckles] Of course zero exists.
Sheldon: Great. Then explain it to me.
Dr. John Sturgis: Easy. Zero is nothing.
Sheldon: But how can nothing be a thing?
Dr. John Sturgis: Think of it this way... Picture an empty box.
Sheldon: All right.
Dr. John Sturgis: What's in the box? Nothing.
Sheldon: It's not nothing. Air, atoms, molecules... That empty box is as full as full can be.

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]

Sheldon: Missy and I broke a lot of rules the other night, and we've received no punishment.
George Sr.: [sighs] Buddy, it's been a rough week. We're just glad you're both safe.
Sheldon: But in the absence of a divine being, society's rules are what keeps a person's morality in check.
George Sr.: Well, there you go.
Sheldon: No, y-you're not following me. If actions have no repercussions, society breaks down, everything devolves into chaos.
George Sr.: You might be overthinking this.
Sheldon: I thought so, too. Then I thought about it, and I'm not.
George Sr.: Sheldon, you had one bad night. Just let it go.
Sheldon: But... I did something wrong and I got away with it. That's not okay.
George Sr.: Buddy...
Sheldon: Socrates maintained that the man who lies to himself has an enemy living within. He's not even a person. He's just a chaos of selfish desires wrapped in an animal hide.

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.

Meemaw: How about this... Why don't you get one of your girlfriends to find out how he feels about you.
Missy: Why?
Meemaw: Because then you don't have to put yourself on the spot.
Missy: Okay. And if he doesn't like me back, I'll just keep being mean to him until he does.
Meemaw: I don't know why that works. Men are dumb.
Missy: Does that mean we're dumb for liking 'em?
Meemaw: It's not a good look for us.

Sheldon: Okay, your basic arithmetic skills are disappointing but functional.
Billy Sparks: Thank you.
Sheldon: All right, let's talk about negative numbers.
Billy Sparks: I'm all ear.
Sheldon: "Ears."
Billy Sparks: No. "Ear." This one's clogged.

Sheldon: All right, I'm given to understand you have a test coming up on negative numbers and fractions.
Billy Sparks: Yeah.
Sheldon: So, what part don't you understand? [Billy is silent] Oh, boy. Let's take it back a step. Where do you stand on addition, subtraction, multiplication and division?
Billy Sparks: I'm against it.
Sheldon: [exhales] [quietly] Oh, boy.