Balther claims to have derived his information from a biography which he discovered in the monastery of "Helera" on the Moselle,[note 1] also founded by Fridolin.

Johann Peter Kirsch suggests that Balther relied on an earlier verbal tradition for the information recorded in his work.

[5] On the other hand, historian Gerold Meyer von Konau [de] dismisses Balther this as entirely untrustworthy, and considers the Vita a forgery of the mid-11th century.

Fridolin appears to have been an Irish missionary among the Alamanni along the Upper Rhine, who at the time were under Merovingian rule, and he went on to found Säckingen Abbey.

Saint Hilarius subsequently appeared to him in a dream, and commanded him to proceed to an island in the Rhine, in the territories of the Alamanni.

In obedience to this summons, Fridolin approached Clovis I, who granted him possession of the still unknown island, and thence proceeded through "Helion",[note 2] Strasbourg and Coire, founding churches in every district in honour of Saint Hilarius.

Fridolin's connection to Glarus is based on a later legend, a 13th-century addition to Balther's Vita under the title de miraculis s. Fridolini.

On his death Ursus left his lands in the Linth valley (the later canton of Glarus), to Fridolin, who founded numerous churches dedicated to Saint Hilarius.

Ursus's brother Landolf refused to accept the legitimacy of the gift and brought Fridolin before a court at Rankweil to prove his title.