In a word, I much doubt whether it be possible for a cause to be known only by its effect (as you have all along supposed) or to be of so singular and particular a nature as to have no parallel and no similarity with any other cause or object, that has ever fallen under our observation.
Hitz batez, zalantza handian daukat kausa bat bere efektuaren bidez bakarrik (uneoro suposatu duzunez) ezagutua izan daitekeen, edota halako izaera bakan eta berezikoa datekeen, gure behaketaren mendean inoiz gertatu den beste ezein kausa edo objekturekin antzik eta paralelotasunik batere ukan ez dezan.