Saint Gerasimus was a native of Lycia (Asia Minor). From his early years he was distinguished for his piety. Having received monastic tonsure, he withdrew into the desert of the Thebaid (in Egypt). Thereafter, in about the year 450, the monk arrived in Palestine and settled at the Jordan, where he founded a monastery.
For a certain while Saint Gerasimus was tempted by the heresy of Eutyches and Dioscorus, which acknowledged only the divine nature in Jesus Christ, but not His human nature (i.e. the Monophysite heresy). Saint Euthymius the Great (January 20) helped him to return to the true Faith.
Saint Gerasimus established a strict monastic Rule. He spent five days of the week in solitude, occupying himself with handicrafts and prayer. On these days the wilderness dwellers did not eat cooked food, nor did they kindle a fire, but ate only dry bread, roots and water.
On Saturday and Sunday all gathered at the monastery for Divine Liturgy and to partake of the Holy Mysteries of Christ. In the afternoon, taking a supply of bread, tubers, water and an armload of date-palm branches for weaving baskets, the desert-dwellers returned to their own cells. Each had only old clothes and a mat, upon which he slept. When they left their cells, the door was never locked, so that anyone could enter and rest, or take whatever he needed.
Saint Gerasimus himself attained a high level of asceticism. During Great Lent he ate nothing until the very day of the All-Radiant Resurrection of Christ, when he received the Holy Mysteries. Going out into the desert for all of Great Lent, Saint Gerasimus took with him his beloved disciple Saint Cyriacus (September 29), whom Saint Euthymius had sent to him.
When Saint Euthymius the Great died, Saint Gerasimus saw how angels carried the soul of the departed up to Heaven. Taking Cyriacus with him, the monk immediately set off to the monastery of Saint Euthymius and consigned his body to the earth.
Saint Gerasimus died peacefully, mourned by his brethren and disciples. Before his death, a lion had aided Saint Gerasimus in his tasks, and upon the death of the Elder it died at his grave and was buried nearby. Therefore the lion is depicted on icons of the saint, at his feet.