 The term "metabolism" is derived from the Greek Μεταβολισμός – "Metabolismos" for "change", or "overthrow".Aristotle's "The Parts of Animals" sets out enough details of his views on metabolism for an open flow model to be made.He believed that at each stage of the process, materials from food were transformed, with heat being released as the classical element of fire, and residual materials being excreted as urine, bile, or faeces.