6 THE PROGRESS AND SPIRIT OP 



we to include even a small proportion of the systematic or 

 elementary works ; the lectures, memoirs, and addresses to 

 scientific bodies or the articles in periodicals, which, under 

 the influence of this new vigour of enquiry, and the practical 

 popularity of many of its topics, have opened their pages to 

 meet the demand for more familiar information than scien- 

 tific treatises can afford. These topics, in fact, include not 

 only the sciences treating of the simpler inorganic conditions 

 of matter, and the elementary forces (heat, light, electricity, 

 gravitation, and chemical affinity) which act upon the material 

 world ; but also animal and vegetable physiology in their 

 whole extent, and those wonderful laws of organic life, con- 

 necting matter with vitality, instincts and intellect, under the 

 numberless forms and species which are placed before us for 

 our contemplation. In surveying this vast field of natural 

 knowledge for the purposes just indicated, we must of neces- 

 sity limit ourselves to a broad outline ; thereby forfeiting in 

 some part the interest which belongs to the familiar illus- 

 trations of each particular science, but gaining in compen- 

 sation a more comprehensive view of the relation between 

 the different sciences and of those great discoveries in all 

 which are ever tending to bring them into closer connection 

 and subjection to common laws. We need scarcely dwell on 

 the importance of such general views, and their influence on 

 the spirit and progress of physical philosophy. We shall 

 have occasion immediately to illustrate it, in speaking of the 

 efforts made by some of the most eminent men of science 

 of our day to give concentration and unity to classes of 

 phenomena hitherto regarded as having no co-relation or 

 common principle of action. 



We do not undertake to analyse in detail, or even to 

 notice, all the works before us. To one of them, however, 

 the Essays of Professor Baden Powell, we must refer, as ex- 

 pounding more distinctly than any other, that present spirit 



