When were beads invented, and what do they symbolize?

The Catholic Answers

It is impossible to say when beads were first used. As an aid to memory, the early Christians used to put a number of pebbles in one pocket, transferring them to another as they said each prayer, so that they could be sure of completing such prayers each day as their devotion inspired. Later, berries or pebbles were strung together for the purpose. In the middle ages sections of these beads were adapted to the different meditations which compose the Rosary, the sections being a numerical help to meditate for a given period of time upon each allotted subject. The symbolism is expressed in the word Rosary. A Rosary is a garland of flowers. One rose does not make a Rosary. Prayers are the flowers of the spiritual life, and in offering that group of prayers, known as the Rosary, we lay a garland of spiritual flowers at the feet of God.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty