In religion and mythology

The frog is a symbol of reincarnation, for it goes through several forms from eggs to the tadpole breathing through its gills to the air-breathing adult. It is likened to the many forms a soul may be born in.

There is an entire philosophic treatise, the Mandukya Upanishad, which explains the meaning of the sound AUM as three stages of consciousness: A is the state of wakefulness, O of dreams and M of deep sleep.