RELATIONS OF SCIENCE TO THE PUBLIC WEAL. 237 



seed, they hoped to attain the three sensuous conditions of human en- 

 joyment, gold, health, and immortality. By the end of the fifteenth 

 century many important manufactures were founded by empirical ex- 

 periment, with only the uncertain guidance of science. Among these 

 were the compass, printing, paper, gunpowder, guns, watches, forks, 

 knitting-needles, horseshoes, bells, wood-cutting and copper-engraving, 

 wire-drawing, steel, table-glass, spectacles, microscopes, glass mirrors 

 backed by amalgams of tin and lead, windmills, crushing and saw 

 mills. These important manufactures arose from an increased knowl- 

 edge of facts, around which scientific conceptions were slowly concret- 

 ing. Aristotle defines this as science when he says, " Art begins when, 

 from a great number of experiences, one general conception is formed 

 which will embrace all similar cases." Such conceptions are formed 

 only when culture develops the human mind and compels it to give a 

 rational account of the world in which man lives, and of the objects in 

 and around it, as well as of the phenomena which govern their action 

 and evolution. Though the accumulation of facts is indispensable to 

 the growth of science, a thousand facts are of less value to human 

 progress than is a single one when it is scientifically comprehended, 

 for it then becomes generalized in all similar cases. Isolated facts 

 may be viewed as the dust of science. The dust which floats in the 

 atmosphere is to the common observer mere incoherent matter in a 

 wrong place, while to the man of science it is all-important when the 

 rays of heat and light act upon its floating particles. It is by them 

 that clouds and rains are influenced ; it is by their selective influence 

 on the solar waves that the blue of the heavens and the beauteous col- 

 ors of the sky glorify all Nature. So, also, ascertained though isolated 

 facts, forming the dust of science, become the reflecting media of the 

 light of knowledge, and cause all Nature to assume a new aspect. It 

 is with the light of knowledge that we are enabled to question Nature 

 through direct experiment. The hypothesis or theory which induces 

 us to put the experimental question maybe right or wrong ; still, /)r««- 

 dens questio dimicUiim scientice est — it is half-way to knowledge when 

 you know what you have to inquire. Davy described hypothesis as 

 the mere scaffolding of science, useful to build up true knowledge, but 

 capable of being put up or taken down at pleasure. Undoubtedly a 

 theory is only temporary, and the reason is, as Bacon has said, that 

 the man of science "loveth truth more than his theory." The chang- 

 ing theories which the world despises are the leaves of the tree of sci- 

 ence drawing nutriment to the parent stems, and enabling it to put 

 forth new branches and to produce fruit ; and, though the leaves fall 

 and decay, the very products of decay nourish the roots of the tree 

 and reappear in the new leaves or theories which succeed. 



When the questioning of Nature by intelligent experiment has 

 raised a system of science, then those men who desire to apply it to 

 industrial inventions proceed by the same methods to make rapid 



