The two statements that best summarize the excerpt are:
"Think of a heap of charred wood and all in one flash!", and "In thunder as in sunshine, I stand at ease."
These sentences show the attitude of the salesman trying to convince the narrator by making he afraid of the consequences if he doesn't buy the lightning-rod.
The second sentence shows how the narrator is not afraid nor convinced by the salesman and scolds him, portraying the triumph over human fear.