Nature and Human Studies

When we observe the small heads and unmeaning eyes of birds, we do not expect to find any great amount of intellect among them. They are, however, moved by the same passions and feelings as larger animals, and occasionally exhibit thought and reasoning power. I suspect, indeed, could we understand their language, that we should find they can talk to each other, and express their meaning as well as others of the brute creation. The following pages will deal with prominent features of their intelligence and psychology.

What are Species? In its most general acceptation the word "species" signifies a kind or sort of something, which something is the genus to which the species belongs. Thus, a black stone is a species of the genus stone; a gray horse is a species of the genus horse; a scalene triangle is a species of the genus triangle; and, generally, it may be said that every adjective denotes a species of the genus indicated by the substantive to which it is applied. In the technology of the physical sciences the term "species" has a more restricted signification. It is used to denote a group of individuals which corresponds with an early stage of that process of abstraction by which the qualities of individual objects are arranged in the subordinated categories of classification. The individual object alone exists in Nature; but, when individual objects are compared, it is found that many agree in all those characters which, for the particular purpose of the classifier, are regarded as important, while they differ only in those which are unimportant; and those which thus agree constitute a species, the definition of which is a statement of the common characters of the individuals which compose the species...