In allusion to the study which Cauchy had made of the mechanistic theory of the reflection of light, Père Gratry threw out the suggestion that one on the greatest intellectual joys of the great geometrician in the future life would be to penetrate into the secret of light. To which Cauchy replied that it did not appear to him to be possible to know more about this than he himself already knew, neither could he conceive how the most perfect intelligence could arrive at a clearer comprehension of the mystery of reflection than that manifested in his own explanation of it, seeing that he had furnished a mechanistic theory of the phenomenon.
Eta Cauchyk argiaren isladapenaren teoria mekanikoaz eginiko ikerketak zirela eta, aita Gratryk geometra burutsuaren gozamen intelektual handienetako bat argiaren sekretuan barnetzea litzatekeelako ideia atera zuen, eta horri Cauchyk ihardetsi zion esanez ez zitzaiola iruditzen horretan jadanik zekiena baino gehiago jakin ahal zitekeenik, eta ez zitzaiola bururatzen adimenik gorenak berak ere isladapenaren misterioa berak azaldu zuen baino hobeki ulertu ahal izatea, fenomenoaren teoria mekanikoa emana zuenez gero.