The success it gained was doubtless due in some degree to the difficulty which most men had in comprehending it, for it was enwrapped in alluring mystery, but more to the confidence with which it was announced as being the long-looked-for key to the wonders of creation, since its promoters did not hesitate to term it the discovery of " the Natural System," though they condescended, by way of explanation to less exalted intellects than their own, to allow it the more moderate appellation of the Circular or, Quinary System.
But, confining ourselves to what is here our special business, it is to be remarked that perhaps the heaviest blow dealt at these strange doctrines was that delivered by Rennie, who, in an edition of Montagu's Ornithological Dictionary (pp. xxxiii.-1v.), published in 1831 and again issued in 1833, attacked the Quinary System, and especially its application to ornithology by Vigors and Swainson, in a way that might perhaps have demolished it, had not the author mingled with his undoubtedly sound reason much that is foreign to any question with which a naturalist, as such, ought to deal - though that herein he was only following the example of one of his opponents, who had constantly treated the subject in like manner, is to be allowed.
It may be convenient here to deal with the theory of the Quinary System, which was promulgated with great zeal by its upholders during the end of the first and early part of the second quarter of the 19th century, and for some years seemed likely to carry all before it.