The desire for freedom is the topic shared between the two spirituals.
We can arrive at this answer because:
The two spirituals present freedom as their main theme.
In "Go Down, Moses" we can see instructions on how Moses was to seek the freedom of the Hebrews when they were enslaved by the Egyptians.
In "Follow the Drinking Gourd" we can see directions and escape routes, which would give freedom to enslaved people.
It is possible to reach these conclusions from the reading of the two spirituals, where freedom is presented as a topic of great importance and that must be pursued in any circumstance.
