A few days had passed since Ning had left to search for the spirits.
In the easternmost edges of the grassland, he had found Terra.
Terra was a feminine spirit that couldn't speak or even have conscious thoughts. She hid around giant rocks, that were impossible to traverse without being able to fly over the rock or in some other fashion get to her.
At first, the spirit was immediately scared the moment Ning and Saphandra arrived at her hiding place, but when they didn't do anything and just stuck around, her curiosity took the better of her and she came out.
Ning took the opportunity to bond with her. There was really just a single thing he could say to entice the spirit.
"Come with me and I'll take you to see the stars," he told the spirit.
When the spirit realized he was talking about the sparkling things she always saw in the night, she immediately accepted the bond.