During the reign of Emperor Valens, the Arians, with the emperor’s assistance, vehemently persecuted the Orthodox. Hearing of this persecution, Isaac, a hermit somewhere in the east, left the wilderness and came to Constantinople to encourage the faithful and denounce the heretics. At the same time, the Emperor Valens departed to the north with his army against the Goths, who had come down from the Danube toward Thrace. Isaac came before the emperor and said to him: “O Emperor, open the churches of the Orthodox, and God will bless your path.” The emperor ignored the elder and proceeded on his way. The following day, Isaac ran out again before the emperor, and again he repeated his warning. The emperor almost heeded the elder, but a certain advisor of his, a follower of the Arian heresy, prevented him. Isaac ran out before the emperor on the third day, grabbed the emperor’s horse by the reins, begged the emperor to grant freedom to the Church of God, and threatened him with divine retribution if he acted contrary to his petition. The enraged emperor ordered that the elder be thrown into a chasm of mud and thorns. However, three angels appeared and pulled the elder out of the chasm. On the fourth day Isaac came before the emperor and prophesied a terrible death for him if he did not grant freedom to the Orthodox: “I am speaking to you, O Emperor. You will lead the army against the barbarians, but you will not be able to endure their attack. You will flee from them, but you will be captured and burned alive.” Thus is happened. The barbarians cut down the Greek army like grass, but the emperor, with his Arian advisor, fled and hid in a basket. The barbarians arrived at that place and, learning where the emperor was, surrounded the basket and set it afire. Both the emperor and his advisor were burned alive. Following this, Theodosius the Great was crowned emperor. Theodosius, who heard about the prophecy of Isaac and its fulfillment, summoned Isaac and prostrated himself before him. Since peace reigned in the Church and the Arians were exiled, Isaac wanted to return to his wilderness, but he was persuaded to remain in Constantinople. An aristocrat, Saturninus by name, built a monastery for the Elder Isaac, where he lived a life of asceticism until his death, working many miracles. The monastery overflowed with monks and became a great monastery. Before his death, Isaac appointed his disciple Dalmatus as abbot, after whom this monastery was later named. The God-pleasing Elder Isaac entered into eternity in the year 383, to rejoice in the vision of the face of God.
Source: St. Nikolai Velimirovic, The Prologue of Ohrid – Volume One.
The image of God, was faithfully preserved in you, O Father. For you took up the Cross and followed Christ. By Your actions you taught us to look beyond the flesh for it passes, rather to be concerned about the soul which is immortal. Wherefore, O Holy Isaakios, your soul rejoices with the angels.