“Listen, this is just a dream. But very clever people can hear dreams. So please, just listen. I know you’re afraid, but being afraid is all right. Because didn’t anyone ever tell you fear is a super power? Fear can make you faster, and cleverer, and stronger. And one day, you’re going to come back to this barn and on that day you are going to be very afraid indeed. But that’s okay. Because if you’re very wise and very strong, fear doesn’t have to make you cruel, or cowardly, fear can make you kind. It doesn’t matter if there’s nothing under the bed or in the dark, so long as you know it’s okay to b afraid of it. So listen. If you listen to nothing else, listen to this. You’re always going to be afraid, even if you learn to hide it. Fear is like a companion. A constant companion always there. But that’s okay, as fear can bring us together. Fear can bring you home. I’m going to leave you something just so you’ll always remember. Fear makes companions of us all.”
— Clara, Listen
River’s narration: [as the Doctor walks away from the Library] When you run with the Doctor, it feels like it’ll never end, but however hard you try you can’t run forever. Everybody knows that everybody dies and nobody knows it like the Doctor, but I do think that all the skies of all the worlds might just turn dark if he ever, for one moment, accepts it.
River’s narration: Everybody knows that everybody dies, but not every day. Not today. [The Doctor uploads her into CAL, where she is “saved” in a virtual reality, along with her fellow expiditioners killed by the Vashta Nerada] Some days are special. Some days are so, so blessed. Some days, nobody dies at all. Now and then, every once in a very long while, every day in a million days, when the wind stands fair and the Doctor comes to call, everybody lives.
— River Song, Silence in the Library
Martha: Don’t you want to know what I was really doing when I was walking the Earth?
The Master: [rolls his eyes] Go on then, tell me.
Martha: I told a story. That’s it. No guns, no bombs, just words. I told them about the Doctor. I told them my story, and I told them to pass it on, to tell everyone they could so that the whole world know.
The Master: [mockingly] So faith and hope…That’s your plan?
Martha: No. I gave them an instruction; I told them that if everyone thinks of one word at one specific time-
The Master: Nothing will happen! Prayer, is that your weapon?
Martha: -Right across the world! One word, just one thought, at one moment…But with fifteen satellites!
The Master: [freezes] What?
Jack: The Archangel Network.
Martha: A telepathic field, binding the whole human race together. All of them, every single person on Earth, thinking the same thing at the same time! And that word, is “Doctor”!
— Martha Jones, Last of the Time Lords
Jackson Lake: Tell me one thing. All those facts and figures I saw of the Doctor’s life, you were never alone. All those bright and shining companions. But not anymore?
The Doctor: No.
Jackson Lake: Might I ask why not?
The Doctor: They leave. Because they should. Or they find someone else. And some of them— some of them forget me. I suppose in the end… they break my heart.
— Tenth Doctor, The Next Doctor
This is such a sad quote (especially if you know the story behind “the one who forgot”), but I love what it explains about the Doctor’s life and the problems that come with living a long life. It also explains why he sometimes decides that he should travel alone, which is never actually a good decision. When you lead the type of life the Doctor lives, and you live it for as long as he does, you inevitably lose people. And this Doctor, who is funny and clever, and has more adventures than you can count, also gets his heart broken time and time again. But ultimately he always finds someone new to travel with. Because he has to. Because it’s not good, especially for him, to travel alone for any great length of time. He loses perspective, and sometimes he gets carried away. Sometimes The Doctor needs friends to remind him of what kind of man he is.