12 PRINCIPLES OF SCIENCE. 



ledge, properly so called, does not simply con- 

 sist in the impressions made on the senses by 

 the operations of external phenomena ; true 

 knowledge can only be admitted to exist, when 

 we are in full possession of the cause whence 

 the effects are derived ; and he alone can be 

 denominated the man of science, who is able to 

 connect the cause with the effect. 



These principles are not only more powerful 

 and true than the thing produced, but the ac- 

 tual cause of its production : they possess the 

 power of imparting their own efficacy and 

 energy to the bodies on which they operate, and 

 they constitute the cause whence secondary 

 effects are made to flow: by which, the principle 

 of life, for example, resident in the semina of 

 plants, or in the ova of animals, is enabled to 

 act on matter dead and common, and to convert 

 it to a living state ; by which, the sun, as the 

 principle and fountain of light, becomes the pri- 

 mary cause of illumination in general; by which, 

 the expansibility of air is enabled to excite mo- 

 tion in matter, passive and inert. Many men, 

 who have not learned the principles of parti- 

 cular sciences, can frequently assign reasons, 

 or the cause why, for the effects which they 

 behold ; they seem, intuitively, to possess a de- 

 gree of science, and to attain rules by chance, 

 which instruction is especially designed to un- 

 fold. Mr. HARRIS, therefore, very accurately 



