254 PHYSICAL SCIENCE IN THE MIDDLE AGES. 



relative lengths of the seasons were sufficient data 

 for determining the form of the sun's orbit ; thus 

 Archimedes, possessing a steady notion of mechani- 

 cal pressure, was able, not only to deduce the pro- 

 perties of the lever and of the center of gravity, 

 but also to see the truth of those principles respect- 

 ing the distribution of pressure in fluids, on which 

 the science of hydrostatics depends. 



With the progress of such distinct ideas, the in- 

 ductive sciences rise and flourish ; with the decay 

 and loss of such distinct ideas, these sciences become 

 stationary, languid, and retrograde. When men 

 merely repeat the terms of science, without attaching 

 to them any clear conceptions ; when their appre- 

 hensions become vague and dim; when they assent 

 to scientific doctrines as a matter of tradition, rather 

 than of conviction, on trust rather than on sight ; 

 when science is considered as a collection of 

 opinions, rather than a record of laws by which 

 the universe is really governed ; it must inevitably 

 happen, that men will lose their hold on the know- 

 ledge which the great discoverers who preceded them 

 have brought to light. They are not able to push 

 forwards the truths on which they lay so feeble 

 and irresolute a hand ; probably they cannot even 

 prevent their sliding back towards the obscurity 

 from which they had been drawn, or from being 

 lost altogether. Such indistinctness and vacillation 

 of thought appear to have prevailed in the station- 

 ary period, and to be, in fact, intimately connected 





