Its invention is attributed to Saint Pachomius in the fourth century as an aid for illiterate monks to accomplish a consistent number of prayers and prostrations. Monks were often expected to carry a prayer rope almost constantly, to remind them to pray constantly in accordance with Saint Paul's injunction in I Thessalonians 5:17, "Pray without ceasing."
In some Russian Orthodox service books, certain liturgies can be replaced at need by praying the Jesus Prayer a specified number of times, anywhere from 300 to 1,500 times depending on the service being replaced. In this way prayers can still be said even if the service books are unavailable for some reason. The use of a prayer rope is a very practical tool in such cases, simply for keeping count of the prayers said.
See also: Prayer
Compare with: Rosary