Next morning they say their goodbyes. He tries to give them his famous self-portrait, but of course they do not take it. He calls Amy blessed, and beautiful, and kisses her goodbye. He asks her to marry him, to have "children by the dozen" with him, and she giggles. He throws his arms around the Doctor. "We have fought monsters together, and we have won. On my own, I fear I may not do as well." Hope isn't a blessing. He looks at Amy, and she's a little bit older now. A little bit more of a time traveler, as she begins to wonder if anything can save him.
("It's not that I don't like them. I find them complex. Always somewhere between living and dying. Half-human, as they turn to the sun. A little disgusting.")
On their way to the TARDIS, the Doctor can't stop thinking there's something else, some loving thing that he can do, to mark this place in time. They turn around, as two, as one, and head back to his villa. He takes the TARDIS pretty much in stride -- "How come I'm the crazy one, and you two have stayed sane?" -- and they do a little song and dance for him. Literally, it's brilliant: He shows Vincent one lever, which plays soothing music, and Amy dances about, hopping from foot to foot, as they take him in.
They take him to the mighty Musée d'Orsay. He loves it, every step of every staircase, past Perseus holding Medusa's head aloft: The monster you can't look at, brighter than the sun.
The Doctor comes again to Bill Nighy, just far enough away that Vincent can hear him ask about Vincent. "Big question. But to me, Van Gogh is the finest painter of them all. Certainly the most popular great painter of all time, the most beloved. His command of color the most magnificent. He transformed the pain of his tormented life into ecstatic beauty. Pain is easy to portray, but to use your passion and pain to portray the ecstasy and joy and magnificence of our world... No one had ever done it before. Perhaps no one ever will again. To my mind, that strange, wild man who roamed the fields of Provence was not only the world's greatest artist, but also one of the greatest men who ever lived."
Vincent van Gogh is crying.
Somewhere between living and dying. The Doctor takes him in his arms, apologizing, wiping at the tears. "Vincent, I'm sorry. I'm sorry. Is it too much?" He holds onto the artist like they're holding each other up. Vincent throws his arms around the Doctor, squeezing him tightly, smiling brighter than anything. He stumbles to the docent, kissing him soundly, and he thanks the Doctor. He promises to change. He promises things will be better, from now on. The Doctor looked into the box and found the Hope still clinging there. It wasn't cruelty, it was love.