The notion that our brother, Baby B, who we knew from dreams, could exist inside my body, having somehow gotten in, and needing someday to get out, filled me with panic and—because it’s the nature of humans to be conflicted—longing.

“No, thank you,” I said.

“In Japan, they’re called mizuko,” my mother said. “Water babies. They float around us in the spirit world, waiting for a chance to be born again. I feel him everywhere I go.”

“Water baby,” Lucas said, laughing.

“Water baby,” my mother said.

I couldn’t stop thinking about it: the idea of sex, that wondrous, frightening unknown all mixed up with the idea of pregnancy, and all of that mixed up with the idea of a hovering baby brother who haunted us, wanting to be born.

“He’s patient,” my mother told us. “He’ll wait until the time is right.”

This was how Lucas learned to believe the unbelievable, from our mother, a champion believer. After we were born, and Baby B died, she not only believed in psychotherapy and chiropractic, she believed in acupuncture, homeopathy, past life regression, and soul retrieval. She believed in the power of yoga, astrology, tarot, and craniosacral therapy. Each belief replaced the one before. When she moved on to a new belief—soul retrieval for instance—her fervor for the previous belief dimmed and gradually faded out of the framework of her life. This search lasted until she died. She had an entourage of women her age who were looking for health, meaning, a sense of well-being, power, purpose, or reassurance. She was always searching, scouring—for something we couldn’t give her.

I was a teenager when she was at the height of her self-searching. The things that glowed bright and holy for her never did for me. But I learned from her that belief was a way of exploring the world. Belief brought you to the edges of what might be, rather than keeping you safe in the insular is. It was an act of courage to believe, she thought. Lucas thought so, too.

No wonder Lucas spent so much time trying to bring him back to us. Lucas began turning lights on for Baby B when we were still tiny. Three years old. Four years old. He left a night-light on in the hallway in case Baby B came back in the night. Then he started leaving the bathroom light on. Then the hallway light, the kitchen light, the closet light.

“We can’t sleep when the lights are on,” my parents told him.

“How will he find the house in the dark?” Lucas asked.

“He doesn’t need to see,” my mother said. “It doesn’t work like that.”

“Do you know that for sure?” he asked, and of course she didn’t.