Which does the phrase "word nest" in this analogy most likely represent?

"As the marsh-hen secretly builds on the watery sod,
Behold I will build me a nest on the greatness of God:
I will fly in the greatness of God as the marsh-hen flies
In the freedom that fills all the space ’twixt the marsh and the skies"
(from "The Marshes of Glynn" by Sidney Lanier)