He was born in Moscow in 1337, and took up the monastic life while young. Though he desired a life of strict silence and solitude, he was made abbot of the Simonov Monastery against his will. After a few years, obeying a revelation from the most holy Theotokos, he left his abbacy and went to the wilderness of Belozersk (White Lake) to live as a hermit. Others gathered there to live under his guidance, and in time the community became the Monastery of Belozersk. Saint Kyril was sought from far off as a staretz, or spiritual father, and was granted gifts of wonderworking. His humility was remarkable, as the following story shows.
Once one of his monks conceived a terrible hatred for Kyril, which tormented him for a whole year. Finally the monk worked up the courage to reveal his hatred to Kyril himself. Though the monk was full of shame and remorse at his malicious passion, Kyril comforted him and said, ‘All the others are in error about me; only you have perceived my unworthiness.’ Saint Kyril then forgave the man and sent him away with his blessing.
Saint Kyril reposed in peace in 1427, at the age of ninety.