Martin Heidegger (1889-1976) is one of the most influential - and controversial - philosophers of the twentieth century. He is mostly associated with existentialism (the study of human experience) and phenomenology (the study of consciousness), and his work was enormously influential.

In this story, Heidegger is exploring the relationship between 'beings' and their environments. How much does each - the rock, the lizard and the human - understand of the world around them?

By adapting famous animal parables, the Pocket Philosophy series seeks to introduce inquisitive readers of all ages - from 1 to 100! - to the biggest names in philosophy.