Water also dissolves a wide 
range of substances, so that it helps
 to carry essential nutrients and 
elements to organisms that need
 them. Without water’s exception
al ability to host ions (electrically 
charged atoms and molecules), we
 wouldn’t have photosynthesis or
 nerve impulses. The large surface 
tension of water makes it possible 
for sap to rise up great distances
 through capillary action, so that plants can stand tall. And so on.

This was deeply puzzling. How could an environment acquire fitness? After all, the chemical ingredients of a planet—water, rocks, air—don’t mutate and reproduce, the key attribute for achieving Darwinian fitness. Yet some of these vital attributes of water had been noted before. In the mid-19th century, several British scholars were commissioned by the Earl of Bridgewater to write a series of books showing “the Power, Wisdom, and Goodness of God, as manifested in the Creation”—in other words, how God’s wisdom was revealed in the discoveries of science, an objective called natural theology. In one of these Bridgewater Treatises, published in 1834, the English chemist William Prout asserted that liquid water’s expansion close to its freezing point was an example of this divine providence.

Henderson was not so ready to cede ground to God, but he admitted that it was not easy to find any alternative explanation for water’s apparent “fitness.” All he could say was that there was “exceedingly little ground for hope that any single explanation of these coincidences can arise from current hypotheses and laws.” If they are ever to be understood, he said, “it will be in the future, when research has penetrated far deeper into the riddle of the properties of matter.”