What Sustains Life?

In the sixth century BC, Thales of Miletus, father of the Ionian Enhghtenment, setting aside the mythic views of Homer and Hesiod asked, "What is the world made of?" and thereby became the first physicist.^ He answered that water is the basis of all matter and thereupon became an often cited example of early Greek reasoning gone astray. However, not only did Thales initi­ ate scientific inquiry, but also, with reference to living things, he was substantially correct. Living organisms are composed mostly of water, but the unique role of water in living organisms has been wanting for adequate description. From the perspective of D.H. Lawrence, "Water is H2O, hydrogen two parts, oxygen one part, but there is a third thing that makes it water and nobody knows what that is." From our perspective and as advanced in this volume, the interaction of water with dissimilar groups compris­ ing each protein molecule, the competition for water between these disparate substituents along chain molecules of living organisms, and the freedom of motion that water gives protein chains combine to provide the physical basis of Life.