Water-fowl adopt a somewhat different mode of alighting upon land, or even upon ice, from that which they adopt when alighting upon water; and those kinds which dive from a height (such as terns and gannets) never do so upon land or upon ice. These facts prove that the animals have one recept answering to a solid substance, and another answering to a fluid. Similarly, a man will not dive from a height over hard ground or over ice, nor will he jump into water in the same way as he jumps upon dry land. In other words, like the water-fowl, he has two distinct recepts, one of which answers to solid ground, and the other to an unresisting fluid. But, unlike the water-fowl, he is able to bestow upon each of these recepts a name, and thus to raise them both to the level of concepts. So far as the practical purposes of locomotion are concerned, it is of course immaterial whether or not he thus raises his recepts into concepts; but, as we have seen, for many other purposes it is of the highest importance that he is able to do this. Now, in order to do it, he must be able to set his recept before his own mind as an object of his own thought: before he can bestow upon these generic ideas the names of “solid” and “fluid,” he must have _cognized_ them _as_ ideas. Prior to this act of cognition, these ideas differed in no respect from the recepts of a water-fowl; neither for the ordinary requirements of his locomotion is it needful that they should: therefore, in so far as these requirements are concerned, the man makes no call upon his higher faculties of ideation. But, in virtue of this act of cognition, whereby he assigns a name to an idea known as such, he has created for himself—and for purposes other than locomotion—a priceless possession: he has formed a concept.