Poirot is world famous for the strength of his "little grey cells" and his skill of detection. In Murder on the Orient Express, though, Poirot is up against some pretty strong and skilled minds. There's the Russian Princess Dragomiroff, who has an iron will; Mary Debenham, who is cool, cold, and rational; and we can't forget the famous actress, Linda Arden, who plays the role of Mrs. Hubbard with great gusto. Who's mind is the best them all?
The passengers would have displayed greater strength if they had been able to resist taking revenge on Ratchett.
Strength of mind is the supreme virtue.