12 PROGRESS OP HUMAN KNOWLEDGE. 



the progress of physical science applies also to the 

 knowledge got by observation. Here, again, the genius 

 of the age has invented instrumental aids, so augment- 

 ing the natural powers of the eye as to give access to 

 that which is greatest and that which is least in the 

 world around us. The telescope and microscope, 

 both modern creations, have attained what may almost 

 seem the limit of perfection. But, apart from these 

 instrumental means, the whole theory and practice of 

 observation has undergone a conspicuous change. Phe- 

 nomena, in every part of the natural world, disregarded 

 before, are now registered in the great volume of 

 Science the simplest and most familiar often disclos- 

 ing truths which are denied to more recondite research. 

 Observation in its methods and records has become 

 almost a science in itself. The senses even have been 

 so tutored into obedience to the intellect as in some 

 degree to augment their natural powers ; while the in- 

 stant embodiment of every new fact observed in some 

 record of prior knowledge gives both motive and direc- 

 tion to those who labour in this large and fertile field. 



These new and various resources of physical enquiry 

 have not merely extended all the sciences of older 

 time, but have given origin to others unknown as such. 

 Electricity, including the cognate phenomena of Mag- 

 netism, is the most striking example ; since the very 

 power itself, though pervading our globe, and probably 

 worlds beyond, may almost be deemed a recent dis- 

 covery. Though dealing with elements more familiar 

 to the senses, the sciences of Light and Heat are vir- 

 tually the creation of the last two centuries. The know- 



