Ardo was a monk of the Abbey of Ariane, in the diocese of Montpellier. He was originally called Smaragdus, and was one of the first disciples of St. Benedict of Ariane, whose Life he wrote. Many other works go under the name of Smaragdus; but there is a great controversy among the learned whether they belong to this or another writer. The Life of St. Benedict is certainly his, and may be found in Menardus, Observ. ad Martysiolog. Benedict. lib. ii; also in Mabillon, Scec. Benedict. 4:1. He was highly esteemed by Charlemagne, and died March 7, 845, aged sixty. 'See Cave, Historia Literaria, ii, 23.