The purely scientific side of ornithology (and of botany, too, it must
be confessed) is as yet too much of a makeshift to be very captivating,
even to those whose predilections are of an intellectual rather than of
a sentimental sort. Its principles of classification are not yet very
profoundly established, and by the highest authorities upon the subject
are confessedly tentative. In counting the number of feathers in the
wing, and in examining the anatomy of a bird's foot, for tests of
relationship, we hardly penetrate deep enough into the real nature of a
bird to feel any intense glow of enthusiasm. Swallows, warblers, and
finches are temperamentally different; - a difference by no means
accounted for by existing criteria of classification. And botany is not
in advance of ornithology in this respect.