According to the legend, the monastery was founded in 1136 by Siginand, prior of the abbey of Moutier-Grandval, who got lost in the deep forest of the High Jura while hunting a wild boar and was unable to find his way out. He vowed to found a monastery if he managed to return safely to Moutier, which he did four days later. To the monastery he founded in accordance with his vow he gave the name of "belle laie" ("laie" is a female wild boar).