The Monk Gerasimus was a native of Lycia (Asia Minor). From his early years he was distinguished for his piety. Having then accepted monasticism, the monk withdrew into the depths of the Thebaid wilderness (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 Eutychius and Dioscorus, which acknowledged in Jesus Christ only the Divine nature, but not His human nature (i.e. the Monophysite heresy). The Monk Euthymius the Great helped him to return to the true faith.
At the monastery the Monk 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 even kindle a fire, but rather ate only dry bread, roots, and water. On Saturday and Sunday all gathered at the monastery for Divine Liturgy and to commune the Holy Mysteries of Christ. In the afternoon, taking with them a supply of bread, tubers, water, and an armload of date-palm branches for weaving into baskets, the wilderness dwellers returned to their own cells. Each had only old clothes and a mat, upon which he slept. In exiting their cells, the door was never secured, so that anyone coming by could enter, and rest, or take along necessities.
The Monk Gerasimus himself attained an high level of asceticism. During Great Lent he ate nothing until the very day of the All-Radiant Resurrection of Christ, when he communed the Holy Mysteries. Going out into the wilderness for the whole of Great Lent, the Monk Gerasimus took along with him his beloved disciple Blessed Cyriacus, whom the Monk Euthymius had sent off to him.
At the time of the death of Saint Euthymius the Great, the Monk Gerasimus saw how Angels carried up the soul of the departed off to Heaven. Taking Cyriacus with him, the monk immediately set off to the monastery of Saint Euthymius and consigned his body to earth.
The Monk Gerasimus himself died peacefully, wept over by brethren and disciples. Before his death, a lion had aided the Monk Gerasimus in his tasks, and upon the death of the elder it too died at his grave and was buried nearby. And therefore the lion is depicted on icons of the saint, at his feet.