This reminds me of a passage from the previous chapter that I had underlined and should have mentioned earlier.
Eomer speaking to Aragorn after asking for privacy from the rest of the Mark--"All that you say is strange, Aragorn,' he said. "Yet you speak the truth, that is plain: the Men of the Mark do not lie, and therefore they are not easily deceived. As long as I am quoting old material- there was another passage from "The Riders of Rohan" that made a deep impression on me.
Again, Eomer to Aragon, "How shall a man judge what to do in such times?"
Aragorn replies; "Good and ill have not changed since yesteryear, nor are they one thing among Elves and Dwares and another amoung Men. It is a man's part to discern them, as much in the Golden Wood as in his own house."
Sorry, I should have been more agile, and mentioned this in the previous chapter.
The converse of the first quote is pure scripture - - "....men will go about deceiving and being deceived."