| Quote #1
He sipped his wine. Then, leaning back, he ran his eye thoughtfully round the dining car. There were thirteen people seated there and, as M. Bouc had said, of all classes and nationalities. He began to study them. (1.3.13)
Ever observant, even when he isn't on a case, Poirot is a student of human nature. This certainly helps him later when he decides to solve the Ratchett murder mystery.
| Quote #2
"I know something of your methods. This is the ideal case for you. To look up the antecedents of all these people, to discover their bona fides ¬– all that takes time and endless inconvenience. But have I not heard you say often that to solve a case a man has only to lie back in his chair and think? Do that. Interview the passengers on the train, view the body, examine what clues there are and then – well, I have faith in you! I am assured that it is no idle boast of yours. Lie back and think – use (as I have heard you say so often) the little grey cells of the mind ¬– and you will know!" (1.5.141)
Poirot's reputation precedes him, and M. Bouc urges him to use his brainpower to crack the case.
| Quote #3
"See you, my dear doctor, me, I am not one to rely upon the expert procedure. It is the psychology I seek, not the fingerprint or the cigarette ash. But in this case I would welcome a little scientific assistance. This compartment is full of clues, but can I be sure that those clues are really what they seem to be?" (1.7.112)
While Poirot relies mostly upon logic and psychology, we also see he is not opposed to bringing scientific methods into his investigation.