iect. ii.] DISSERTATION SECOND. 99 



solation for the imperfection of our theoretical knowledge, 

 that, in as much as art is concerned, or the possession of 

 power over heat, we have perhaps all the advantages that 

 could be obtained from a complete knowledge of its es- 

 sence. 



An equal degree of mystery hangs over the other pro- 

 perties and modificalions of body; light, electricity, mag- 

 netism, elasticity, gravity, are all in the same circumstan- 

 ces ; and the only advance that philosophy has made to- 

 ward the discovery of the essences of these qualities or 

 substances is, by exploding some theories, rather than by 

 establishing any, — so true is Bacon's maxim, that the first 

 steps in philosophy necessarily consist in negative propo- 

 sitions. Besides this, in all the above instances the laws 

 of action have been ascertained ; the phenomena have been 

 reduced to a few general facts, and in some cases, as in 

 that of gravity, to one only ; and for ought that yet ap- 

 pears, this is the highest point which our science is des- 

 tined to reach. 



In consequence of supposing a greater perfection in 

 knowledge than is ever likely to be attained, Bacon ap- 

 pears, in some respects, to have misapprehended the way 

 in which it is ultimately to become applicable to art. He 

 conceives that, if the form of any quality were known, we 

 should be able, by inducing that form on any body, to 

 communicate to it the said quality. It is not probable, 

 however, that this would often lead to a more easy and 

 simple process than that which art has already invented. 

 In the case of colour, for example, though ignorant of its 

 form, or of the construction of surface which enables bo- 

 dies to reflect only light of a particular species, yet we 

 know how to communicate that power from one body to 

 another. Nor is it likely, though this structure were known 

 with ever so great precision, that we should be able to tva 



