Fukuzawa gives Rampo a pair of glasses, claiming that wearing them would activate his ability to instantly determine the truth of any situation, and taking them off would give him the ability to tolerate the stupidity of the ordinary person.
You guessed the murderer 
in the play earlier.
.خمّنتَ القاتل في المسرح قبل قليل
Prima hai indovinato chi è l'assassino dell'opera.
Você adivinhou o assassino naquela peça.
А сейчас ты легко вычислил,
кто в пьесе убийца.