A man when he is making up to anybody can be cordial and gallant and full of little attentions and altogether charming. But when a man is really in love he can't help looking like a sheep.
I like to inquire into everything. Hercule Poirot is a good dog. The good dog follows the scent, and if, regrettably, there is no scent to follow, he noses around - seeking always something that is not very nice.
There is nothing so dangerous for anyone who has something to hide as conversation!... A human being, Hastings, cannot resist theopportunity to reveal himself and express his personality which conversation gives him. Every time he will give himself away.