A Bulgarian who avoided marriage in his youth, he secretly left for Mount Athos. Even then, on the journey, the devil tried to undermine the youth's aspirations, disturbing him with a vision of an insurmountable sea abyss surrounding the Holy Mountain. The youth's fervent prayer dispelled the demonic obsession.
On Mount Athos, Saint Cosmas was accepted into the Zographou Monastery. There, he served as a novice for a long time, then became a monk and was appointed ecclesiarch. Saint Cosmas received the special grace of being a seer of the Heavenly Abbess of Mount Athos, who, on the Feast of the Annunciation at the Vatopedi Monastery, deigned to visibly reveal to him Her care for Her earthly lot: he saw a woman of regal beauty and majesty, who presided over both the church services and the refectory, while all the monks were Her obedient servants. Soon, the saint was ordained a deacon, and then a priest, which spurred him on to new ascetic endeavors.
Desiring salvation, the saint – through fervent prayers to the Most Holy Theotokos – was again granted a sign of Her special protection: he heard the voice of the Mother of God, emanating from Her holy icon, asking Her Son, "How can Cosmas be saved?" The Lord's answer was: "Let him leave the monastery for silence." Having received the abbot's blessing, Saint Cosmas withdrew to the desert, and there, in a cave carved into the rock, he began a new ascetic struggle of silent solitude. God did not abandon His faithful intercessor: the saint was granted the gift of clairvoyance.
Just as at the beginning of his ascetic life, the enemy of mankind attempted to divert the saint from his chosen path, so the days before his death were also a grievous trial for the righteous one. Shortly before his death, the God's chosen one was honored with a vision of Christ Himself, who informed the saint that before his soul departed for the Kingdom of Heaven, Satan himself and his horde would cruelly beat and wound him. Prepared for suffering by divine consolation, the saint courageously endured the terrible diabolical mockery permitted by God, and on the third day after the ferocious beating, having received the Most Pure Mysteries, with praise on his lips, he peacefully departed to the Lord. God, "who glorifies those who glorify Him," miraculously glorified Saint Kosmas after death: during the saint's burial, a multitude of animals and birds flocked to his cave, as if understanding the shared loss of the Holy Mountain. When his body was lowered into the grave and covered with earth, each of the dumb creatures emitted a mournful cry, paying its final respects to the saint of God. When – as was customary – 40 days after the all-night vigil, the brethren uncovered the holy remains of the righteous man to transfer them with honor to the monastery, they were miraculously missing — the Lord had concealed them. This was in 1323.
Apolytikion in the First Tone
In the cave where you
have settled, you have been imitating by deeds He Who was born in a
Cave, O Kosmas, most blessed one. You have endured even to the very
death the demonic struggles and have, through grace, become a model.
Your body immortal lasts for ever in the secret treasure until the
Second Judgement and the Resurrection. Glory to Him Who had granted you
firm strength, glory to Him Who had exalted you, glory to Him Who had
made you famous in the Heavenly Kingdom.