IV

It is a significant fact that the four chief elements which in various combinations make up living bodies are by their extreme mobility well suited to their purpose.  Three of these are gaseous; only the carbon is a solid.  This renders them facile and adaptive in the ever-changing conditions of organic evolution.  The solid carbon forms the vessel in which the precious essence of life is carried.  Without carbon we should evaporate or flow away and escape.  Much of the oxygen and hydrogen enters into living bodies as water; nine tenths of the human body is water; a little nitrogen and a few mineral salts make up the rest.  So that our life in its final elements is little more than a stream of water holding in solution carbonaceous and other matter and flowing, forever flowing, a stream of fluid and solid matter plus something else that scientific analysis cannot reach—­some force or principle that combines and organizes these elements into the living body.

If a man could be reduced instantly into his constituent elements we should see a pail or two of turbid fluid that would flow down the bank and soon be lost in the soil.  That which gives us our form and stability and prevents us from slowly spilling down the slope at all times is the mysterious vital principle or force which knits and marries these unstable elements together and raises up a mobile but more or less stable form out of the world of fluids.  Venus rising from the sea is a symbol of the genesis of every living thing.

Inorganic matter seeks only rest.  “Let me alone,” it says; “do not break my slumbers.”  But as soon as life awakens in it, it says:  “Give me room, get out of my way.  Ceaseless activity, ceaseless change, a thousand new forms are what I crave.”  As soon as life enters matter, matter meets with a change of heart.  It is lifted to another plane, the supermechanical plane; it behaves in a new way; its movements from being calculable become incalculable.  A straight line has direction, that is mechanics; what direction has the circle?  That is life, a change of direction every instant.  An aeroplane is built entirely on mechanical principles, but something not so built has to sit in it and guide it; in fact, had to build it and adjust it to its end.

Mechanical forces seek an equilibrium or a state of rest.  The whole inorganic world under the influence of gravity would flow as water flows, if it could, till it reached a state of absolute repose.  But vital forces struggle against a state of repose, which to them means death.  They are vital by virtue of their tendency to resist the repose of inert matter; chemical activity disintegrates a stone or other metal, but the decay of organized matter is different in kind; living organisms decompose it and resolve it into its original compounds.