"External circumstances can be deceptive." Discuss this with reference to the story "Dusk" by Saki.

Of course, the quote you have cited could be argued to be
the main message of this excellent story that uses situational irony so well in its
ending. Note how the story is told using the third person limited point of view, which
means we see everything from Norman Gortsby's perspective, only having access to his
thoughts and feelings. Thus it is that we can see how the young man appears to him as he
is described to us. Gortsby of course exposes the young man's deceit, but then, after
the young man has left the scene, finds a bar of soap by the bench where the young man
was sitting. Ashamed of his judgement and attitude towards the young man, who, Gortsby
believes, has his story proven by this object, he finds the young man, returns the soap
and gives him some money. As he walks back to his bench, he thinks to
himself:

It's
a lesson to me not to be too clear in judging by
circumstances.

Of course, as
he goes back to his bench only to be met by the old man who was sitting next to him at
the start of the story looking for his bar of soap we see that external circumstances
can be incredibly deceptive, and that Gortsby was actually correct about the young man.
He was trying to deceive Gortsby as a confidence trickster, but the "lucky" find of the
bar of soap ironically supported the young man's story, showing that Gortsby should be
"clear" in trusting his intuition and that external circumstances are not always what
they seem.