Musings on ….Proverbs 30 Part 3

15 The leech has two daughters:
Give and Give. 
Three things are never satisfied;
four never say, “Enough”:
16 Sheol, the barren womb,
the land never satisfied with water,
and the fire that never says, “Enough.”
Two daughters, Give and Give
3 things are never satisfied
1. Sheol
2. the barren womb
3. the land with water
and the 4th fire never says enough.
why are these things listed together?  [...]