May 30 Ven. Isaac, Founder of the Dalmatian Monastery at Constantinople (383). SAINT ISAAC OF DALMATIA Saint Isaac lived during the fourth century, received monastic tonsure and pursued ascetic labors in the desert. During the reign of the emperor Valens (364-378), a zealous adherent of the Arian heresy, there was a persecution of the Orthodox, and churches were closed and destroyed. Hearing of the persecution, Saint Isaac left the wilderness