A still more remarkable instance of perverted observation exists in an old book entitled _Metamorphosis Naturalis_, &c., published at Middleburgh in 1662. This work, in which is attempted for the first time a detailed account of insect-transformations, contains numerous illustrative plates, in which are represented the various stages of evolution—larva, pupa, and imago. Those who have any knowledge of Entomology will recollect that the chrysalises of all our common butterflies exhibit at the anterior end a number of pointed projections, producing an irregular outline. Have they ever observed in this outline a resemblance to a man’s face? For myself, I can say that though in early days I kept brood after brood of butterfly larvæ through all their changes, I never perceived any such likeness; nor can I see it now. Nevertheless, in the plates of this _Metamorphosis Naturalis_, each chrysalis has its projections so modified as to represent a burlesque human head—the respective species having different profiles given them. Whether the author was a believer in metempsychosis, and thought he saw in the chrysalis a disguised humanity; or whether, swayed by the false analogy which Butler makes so much of, between the change from chrysalis to butterfly and that from mortality to immortality, he considered the chrysalis as typical of man; does not appear. Here, however, is the fact, that influenced by some {164} pre-conception or other, he has made his drawings quite different from the actual forms. It is not that he simply thinks this resemblance exists—it is not that he merely says he can see it; but his preconception so possesses him as to swerve his pencil, and make him produce representations laughably unlike the realities. These, which are extreme cases of distorted perceptions, differ only in degree from the distorted perceptions of daily life; and so strong is the distorting influence that even the man of science cannot escape its effects. Every microscopist knows that if they have conflicting theories respecting its nature, two observers shall look through the same instrument at the same object, and give quite different descriptions of its appearance.