ON THE NATURE OF LIFE 215 



It must have the " property " of reality — that is, it must not be 

 in contradiction to the law of conservation — for it is to be a 

 means of investigation. Thus we are compelled to reject any of 

 those concepts upon which the theories of spooks are based. It 

 must work — that is, it must lead to the discovery of further 

 workable results or hypotheses — and it must therefore avoid the 

 reproach (addressed originally by Bacon to certain philosophies), 

 and extended to Driesch's " psychoids " by a well-known 

 cytologist, that it is hke the vestal virgins, dedicated to God 

 and barren ! Now it ought to be clear to the reader at this stage 

 in what direction we are seeking for our concept. We have 

 throughout this book kept the notion of energy in the forefront 

 in order that we might lead up to our thesis that the concept 

 which is special to the organism is one which involves the reversal 

 of the second law of thermo- dynamics. We must not be troubled 

 by the strangeness of such a concept or by the appearance of 

 paradox that goes with it. It is not more strange than some 

 notions in mathematics that have, nevertheless, been fruitful of 

 result — than, for instances, the non-Euclidean postulate that more 

 than one line can be drawn through a point and still be parallel 

 to some oth§r line not going through the point ; that the sum of 

 the angles of a triangle may be less than two right angles ; that 

 a negative number may have a square root. The test is that, 

 ylike the notions just given as instances, ours shall have pragmatic 

 value — may work. 



So, again, we contrast the inorganic and organic physico- 

 chemical systems. 



In the former, anything at all that happens of itself happens 

 because energy transformations take a certain direction. This 

 direction is that which leads to a decrease of the differences of 

 intensity in different parts of the system. Available energy is 

 concentrated in this part of the system rather than that, and if 

 it can be levelled down, so to speak, something will happen. If 

 it cannot be levelled down, being equally distributed everywhere, 

 nothing will happen. If water is accumulated in a reservoir at 

 a higher level than that in a lake, it can flow down into the latter, 

 turn a mill-wheel as it flows, and so produce various phenomena. 

 If it is all contained in the lake, if there is no difference of level, 

 there can be no flow, and no energy available for the production 

 of physical phenomena. 



This, then, is the concept by which we " explain " the fact that 



