MENTAL CONSTITUTION OF ANIMALS. 245 



flection of the sun's rays upon sensitive paper are, after a 

 temporary obliteration, resuscitated on the sheet being ex- 

 posed to the fumes of mercury. Such are the phenomena of 

 memory, that handmaid of intellect, without which there 

 could be no accumulation of mental capital, but an universal 

 and continual infancy. Conception and imagination appear 

 to be only intensities, so to speak, of the state of brain in 

 which memory is produced. On their promptness and power 

 depend most of the exertions which distinguish the man of 

 arts and letters, and even in no small measure the cultivator 

 of science. 



The faculties above described the actual elements of the 

 mental constitution are seen in mature man in an indefinite 

 potentiality and range of action. It is different with the 

 lower animals. They are there comparatively definite in 

 their power and restricted in their application. The reader 

 is familiar with what are called instincts in some of the 

 humbler species, that is, an uniform and unprompted ten- 

 dency towards certain particular acts, as the building of cells 

 by the bee, the storing of provisions by that insect and 

 several others, and the construction of nests for a coming 

 progeny by birds. This quality is nothing more than a mode 

 of operation peculiar to the faculties in a humble state of en- 

 dowment, or early stage of development. The cell-formation 

 of the bee, the house-building of ants and beavers, the web- 

 spinning of spiders, are but primitive exercises of construc- 

 tiveness, the faculty which, indefinite with us, leads to the 

 arts of the weaver, upholsterer, architect, and mechanist, and 

 makes us often work delightedly where our labours are in 

 vain, or nearly so. The storing of provision by the bees is 

 an exercise of acquisitiveness, a faculty which with us makes 

 rich men and misers. A vast number of curious devices, by 

 which insects provide for the protection and subsistence of 

 their young, whom they are perhaps never to see, are most 

 probably a peculiar restricted effort of philo-progenitiveness. 

 The common source of this class of acts, and of common 

 mental operations, is shown very convincingly by the melt- 

 ing of the one set into the other. Thus, for example, the 



