<But neither is this [occasional erroneous classification] so important a consideration as that of uniting all nations under one language in Natural History. This had been happily effected by Linnaeus, and can scarcely be hoped for a second time. Nothing indeed is so desperate as to make all mankind agree in giving up a language they possess, for one which they have to learn.>
<[A]dhere to the Linnean because it is sufficient as a ground-work, admits of supplementary insertions as new productions are discovered, and mainly because it has got into so general use that it will not be easy to displace it, and still less to find another which shall have the same singular fortune of obtaining the general consent. During the attempt we shall become unintelligible to one another, and science will be really retarded by efforts to advance it made by its most favorite sons.
And the higher the character of the authors recommending it, and the more excellent what they offer, the greater the danger of producing schism.>
<Linnaeus' method was liable to this objection so far as it required the aid of anatomical dissection, as of the heart, for instance, to ascertain the place of any animal, or of a chemical process for that of a mineral substance. It would certainly be better to adopt as much as possible such exterior and visible characteristics as every traveller is competent to observe, to ascertain and to relate.>
Inarguable insights from a rational perspective considerate of human nature.
Oh, and for those concentrating on the continuity from one form to another:
<This classification was indeed liable to the imperfection of bringing into the same group individuals which, though resembling in the characteristics adopted by the author for his classification, yet have strong marks of dissimilitude in other respects. But to this objection every mode of classification must be liable, because the plan of creation is inscrutable to our limited faculties. Nature has not arranged her productions on a single and direct line. They branch at every step, and in every direction, and he who attempts to reduce them into departments, is left to do it by the lines of his own fancy.>
I had drafted a note using the color spectrum analogy to explain that there are primary colors and shadings from one color to another whose assignment to one color or another is the subject of informative and productive debate. The primary colors, however, are not obscured, just as the difference between lizards and birds is apparent.
Jefferson said it better, so I'll let him answer.
Thanks for the reference!