CARDINAL PRINCIPLES OF SCIENCE 5 



bodies ; this assumption served to pair fundamental notions of 

 matter and motion, the one persisting'only in the particle and 

 the other only in the sum of particles, in such ^manner as to 

 satisfy the dualistic instinct expressed in most earlier philoso- 

 phies ; but at the same time it introduced an indefinite, if not 

 forever indeterminate, element, into the formula — for under 

 the assumption the finality of the formula can never be ascer- 

 tained until the universe is measured and weighed to its ut- 

 termost limits. An alternative assumption, recently proposed 

 by Powell, is that motion, like matter, is persistent in the 

 ultimate particle ; this assumption has the merit of harmon- 

 izing principles otherwise (apparently) discordant, and the 

 special excellence of integrating general human experience ; 

 but it still awaits that direct demonstration through laboratory 

 experimentation, so prearranged as to test all possible infer- 

 ences, which alone carries conviction to conservative minds. 



As Lavoisier's doctrine of indestructibility spread, the method 

 of observation under voluntarily controlled conditions was ex- 

 tended into new fields ; and even while Joule's mechanical ex- 

 periments were still progressing at Manchester, Darwin was 

 arranging a series of vital experiments at Down and comparing 

 his results with the voluminous observations recorded by natur- 

 alists in all parts of the world. Meantime Alfred Russell Wallace 

 and Herbert Spencer were also seeking to organize anew the 

 facts collected on the Linnaean plane, already become chaotic 

 by reason of their very number ; and when the three thinkers 

 independently generalized the teeming experiences of organic 

 life in terms of sequence, the coincident opinions and the in- 

 comparable thoroughness of Darwin's methods combined to 

 force a new principle on an unwilling world of contemporary 

 thought. At first the Darwinian doctrine was burdened by its 

 own infantile feebleness — for there is no Minervan birth in 

 Science — and bound by the swaddlings of scholasticism ; but 

 support came from all sides, and it grew apace and soon be- 

 came the sturdiest of that trinity of scientific principles recog- 

 nized up to the sixth decade of the nineteenth century. For 

 some years the doctrine was largely limited to the organic realm, 

 and was deemed applicable solely to the evolution of animal 



