He was the arbiter of townspeople, of feudal lords and of kings.
He frequently assisted Philip in conducting negotiations with foreign powers, and he was an arbiter in tournaments and on all questions of chivalry, where his wide knowledge of heraldry was highly useful.
At Campo Formio he showed himself the first diplomatist of the age, and the arbiter of the destinies of Europe.
Apart from this system of compulsory reference by the praetor, Roman law recognized a voluntary reference (compromissum) to an arbiter or arbitrator by the parties themselves.
For Erigena, therefore, the speculative reason is the supreme arbiter; and in accordance with its results the utterances of Scripture and of the church have not infrequently to be subjected to an allegorical or mystical interpretation.