The Black Knight

谜语

Once upon a time, there was a knight in black armor who traveled to the Town of Night. He had spent many days there, always taking time to look up at the moon in the sky as it shone overhead. However, he was given a letter to come to the king's castle as soon as possible. The black knight left his room at the inn and walked into the town square. He looked around, searching for his black horse. "Ahh," he said to himself, "there is my black horse, tied to that black tree!" He quickly charged to his horse and mounted it, riding off into the distance.
Now, how was he able to see the horse so easily?

Answer: It must have been daytime in the town of Night.