- The First Doctor: Oh, so you're my replacements - a dandy and a clown. Have you done anything?
- The Second Doctor: Well, we've assessed the situation...
- The First Doctor: Just as I thought - nothing.
- The Doctor: [having fled into the TARDIS] Well, Sergeant, aren't you gonna say that it's bigger on the inside than it is on the outside? Everybody else does.
- Benton: [standing amazed] It's pretty obvious, isn't it?
- The Second Doctor: You see, he is one of me.
- Jo Grant: Oh, I see. You're both Time Lords.
- The Second Doctor: Well, quite. Well... not quite.
- Jo Grant: Oh.
- The Second Doctor: Not JUST Time Lords, we're the SAME Time Lord.
- The Doctor: Now, please, you're only confusing my assistant. Jo, it's all quite simple: I am he and he is me.
- Jo Grant: And we're all together, goo-goo-g'joob?
- Jo Grant: I hate to ask, but who was that?
- The Second Doctor, The Doctor: [to Jo] Me!
- The Second Doctor, The Doctor: [to each other] ME!
- Brigadier Lethbridge Stewart: The thing is, Doctor, is there anything I can do?
- The Doctor: Yes, pass me a silicon rod, will you?
- [a rod is passed to the Doctor, who merely stirs his coffee with it]
- Brigadier Lethbridge Stewart: Yes, what I meant was is there anything that UNIT can do about this space lightning business?
- The Doctor: Lightning? Yes, I suppose it could look like lightning, only it isn't. No, if there were such a thing, I'd say it was compressed light, a sort of controlled superlucent emission.
- President of the Council: Is The Doctor holding out?
- Time Lord: We're giving his TARDIS all the energy we can spare, My Lord.
- President of the Council: And the hostile?
- Time Lord: Unidentified, so far, My Lord.
- Chancellor: Hmm. And the source of this beam?
- President of the Council: You see, Chancellor. A black hole.
- Chancellor: That's a nowhere, no place, a void. According to all known laws, nothing can exist there.
- President of the Council: Yet somehow through this black hole, cosmic energy is draining away in spite of all we can do to check it.
- Time Lord: Already the time travel facility is in danger, My Lord.
- President of the Council: Without it we shall be helpless. Unless the energy loss is stopped, the whole fabric of space time will be destroyed. We are being consumed and we can find no way to fight back.
- Chancellor: Are you telling me we're up against an adversary, a force equal to our own?
- President of the Council: Equal and opposite to our own.
- Chancellor: A force which inhabits a universe, where by definition even we cannot exist?
- President of the Council: Yes. A force in the universe of antimatter.
- Chancellor: But that's too terrible to contemplate. Someone must go and help The Doctor.
- President of the Council: I agree but no-one can be spared, Your Excellency. Everyone is needed to combat the energy drain.
- Chancellor: Are you saying we can't help him?
- President of the Council: Yes I am. But perhaps he can help himself.
- [Turns to Time Lord]
- President of the Council: Show me the Doctor's time stream, the section for his earlier self before he changed his form.
- Chancellor: You cannot allow him to cross his own time stream. Apart from the enormous energy it would need, the first law of time expressly forbids him to meet his other selves.
- President of the Council: I am aware of that, Your Excellency but this is an emergency.
- Chancellor: But you can't.
- President of the Council: Your Excellency, I have to.
- Chancellor: Be it on your own head.