"Well, I suppose you're right, but I can't understand any one running a
risk he could so easily avoid."
"Risk!" Poirot snorted. "Where then lay the risk? Would Japp have
solved the problem? No; if Number Four had not made one small mistake
he would have run no risk."
"And his mistake?" I asked, although I suspected the answer.
"_Mon ami_, he overlooked the little gray cells of Hercule Poirot."
Poirot has his virtues, but modesty is not one of them.