We are always looking for metaphors in which to express our ideas of life, for our language is inadequate for all its complexities. Life is a labyrinth... Life is a machine... Life is a laboratory... It is but a metaphor. When we speak of ultimate things we can, maybe, speak only in metaphors. Life is a dance, a very elaborate and complex dance.

A Short History of Scientific Ideas to 1900, Chapter IX, Section 6 (p. 498), At The Clarendon Press. 1959