The truffle hunter has a nose which, like the eye, is a symbol of clairvoyance, perspicacity and discernment, although more intuitive than reasoned.
The boar (sanglier - from singularum = solitary) searches out the precious truffle that, according to ancient legends, could be the result of the effect of lightning, the fruit of the lightning bolt, the hidden revelation.
Maurice Leblanc, initiated into the mysteries of the story, gradually reveals its secrets via a coded book:
"There were secrets that Arsène Lupin alone knew and whose disclosure, as a result, could only come from him. But for what purpose did he reveal them? And how?" "LES CONFIDENCES D’ARSENE LUPIN"

"Speak, no, but write... I will write my SECRET."
"LES HUIT COUPS DE L'HORLOGE"