The text discusses the notion put forth by naturalists about domestic animal varieties reverting to wild forms over time. This belief suggests that when domestic species return to the wild, they consistently regain traits that resemble their ancestral forms. Such a claim raises questions about the validity of using domestic races to draw conclusions about wild species.

The author expresses frustration at the lack of concrete evidence supporting this widely accepted idea. Despite the frequency and fondness with which this statement is repeated in naturalist discourse, the author finds it challenging to pinpoint decisive facts that substantiate the argument that domestic varieties should not be equated with natural species.