According to scientists, there are three stages of love: lust, attraction, and attachment. And, it turns out, each of the stages is orchestrated by chemicals—neurotransmitters—in the brain. As you might expect, lust is ruled by testosterone and estrogen. The second stage, attraction, is governed by dopamine and serotonin. When, for example, couples report feeling indescribably happy in each other’s presence, that’s dopamine, the pleasure hormone, doing its work. Taking cocaine fosters the same level of euphoria. In fact, scientists who study both the brains of new lovers and cocaine addicts are hard-pressed to tell the difference. The second chemical of the attraction phase is serotonin. When couples confess that they can’t stop thinking about each other, it’s because their serotonin level has dropped. People in love have the same low serotonin levels as people with OCD. The reason they can’t stop thinking about each other is that they are literally obsessed. Oxytocin and desmopressin control the third stage: attachment or long-term bonding. Oxytocin is released during orgasm and makes you feel closer to the person you’ve had sex with. It’s also released during childbirth and helps bond mother to child. Desmopressin is released postcoitally. Natasha knows these facts cold. Knowing them helped her get over Rob’s betrayal. So she knows: love is just chemicals and coincidence. So why does Daniel feel like something more?

— Nicola Yoon

And what about the lovers who spend hours staring into each other's eyes? Is it a display of trust? 'I will let you in close and trust you not to hurt me while I'm in this vulnerable position.' And if trust is one of the foundations of love, perhaps the staring is a way to build or reinforce it. Or maybe it's simpler than that. A simple search for connection To see. To be seen.

— Nicola Yoon

And what about the lovers who spend hours staring into each other's eyes? Is it a display of trust? I will let you in close and trust you not to hurt me while I'm in this vulnerable position. And if trust is one of the foundations of love, perhaps the staring is a way to build or reinforce it. Or maybe it's simpler than that. A simple search for connection. To see. To be seen.

— Nicola Yoon

Anything can happen at any time. Safety is not guaranteed. There's more to life than being alive.

— Nicola Yoon

A photograph is a kind of time machine.

— Nicola Yoon

A universe that can wink into existence can wink out again.

— Nicola Yoon

Be Brave. Remember, life is a gift.

— Nicola Yoon

But can you trust something that can end as suddenly as it begins?

— Nicola Yoon

But I like my big Afro. I also liked when my hair was longer and relaxed. I’m happy to have choices. They’re mine to make

— Nicola Yoon

CARL SAGAN SAID that if you want to make an apple pie from scratch, you must first invent the universe. When he says “from scratch,” he means from nothing. He means from a time before the world even existed. If you want to make an apple pie from nothing at all, you have to start with the Big Bang and expanding universes, neutrons, ions, atoms, black holes, suns, moons, ocean tides, the Milky Way, Earth, evolution, dinosaurs, extinction-level events, platypuses, Homo erectus, CRO- Magnon man, etc. You have to start at the beginning. You must invent fire. Furthermore, you need water and fertile soil and seeds. Furthermore, you need cows and people to milk them and more people to churn that milk into butter. Furthermore, you need wheat and sugar cane and apple trees. Furthermore, you need chemistry and biology. For a perfect apple pie, you need the arts. For an apple pie that can last for generations, you need the printing press and the Industrial Revolution and maybe even a poem. To make a thing as simple as an apple pie, you have to create the whole wide world.

— Nicola Yoon