...finally her hands, so light, holding his head still and catching all his thoughts and imprisoning them there, in the space that no longer existed between them.

Twin primes: pairs of prime numbers that are close to each other, almost neighbors, but between them there is always an even number that prevents them from truly touching. If you go on counting, you discover that these pairs gradually become rarer, lost in that silent, measured space made only of ciphers. You develop a distressing presentiment that the pairs encountered up until that point were accidental, that solitude is the true destiny. Then, just when you’re about to surrender, you come across another pair of twins, clutching each other tightly.

Mattia was right: the days had slipped over her skin like a solvent, one after the other, each removing a very thin layer of pigment from her tattoo, and from both of their memories. The outlines, like the circumstances, were still there, black and well delineated, but the colors had merged together until they faded into a dull, uniform tonality, a neutral absence of meaning.

She found herself thinking of how it would feel to be safely trapped in his arms, with no more possibility to choose.

You can fall ill with just a memory.

You'll get used to it. In the end you won't even notice it anymore," he said. "How is that possible? It will always be there, right before my eyes." "Exactly," said Mattia. "Which is precisely why you won't see it anymore.

Why did you choose to stay here?" (...) "I don't know," he said. "It's as if there's more oxygen here.