A scion of the distinguished line of Bucellini counts, Gabriel, at the age of thirteen, entered the Benedictine monastery at Weingarten.

In the same year he was sent, as master of novices, to restore the primitive fervour and raise the standard of studies in the monastery of St. Trudpert in the Black Forest.

He filled the position of master of novices at Weingarten and professor of humanities at Feldkirch (1635), from which on the approach of the Swedish army he was forced to flee to Vienna, Venice, and finally Admont (1646).

There he was appointed prior of St. John's monastery, Feldkirch (1651), where he remained until a few months before his death, when he returned to Weingarten.

His chief claim to contemporary fame lies in the fact that he was, if not the first, at least among the first authors to deal with the ecclesiastical history of Germany.