It was probably the Japanese who had the idea of using stepping stones in gardens. They were used (1) in paths (2) to cross streams (3) to cross ponds. The aim was to allow participants in a tea ceremony to step through a garden with out disturbing either natural world or their fine clothes.
Stepping stones also have symbolic roles, symbolising steps through life and steps towards an afterlife.
Children love stepping stones.
Stepping stones can be made of: