“I cannot live in the darkness.”
“But I cannot survive in the light.”
In a different universe, life is divided into two parts- the darkness and the light. There is no gray area; there is no place where dark coincides with light. There is no day and night. There is only day. Or there is only night. Thus, creatures function in either or. There is no such thing as both. The only form of communication between the two races is a film of water between their worlds, which can only carry sounds.
“But I am day, and you are night.”
“And if I am night and you are day, how can I ever lay eyes on you? Or touch you?”
“I want to touch you. I want to see you. But if I go into the darkness, my light will go out.”
“And if I go into the light, I will become but a shadow and nothing more.”