Lop-Ear and I did not think of it either until our increasing size compelled us to make an enlargement.

This occurred when summer was well along and we were fat with better forage.

We worked at the crevice in spells, when the fancy struck us.
At first we dug the crumbling rocks away with our fingers, until our nails got sore, when I accidentally stumbled upon the idea of using a piece of wood on the rock.

This worked well.

Also it worked woe.
One morning early, we had scratched out of the wall quite a heap of fragments.