Men would naturally doubt of fish in trees. Even the Chinese would. "To climb a tree in pursuit of fish," is a phrase actually used as an hyperbole of nonsense by many Tsze, in the book called "Shang Mung." And the above is therefore a fair instance of the progress of human intelligence,--of a thousand years of incredulity, and final scientific admission. Let it be taken here as absinthe, appetizingly.
The ancients believed, among other things, that man had, to say the least, relations in the various departments of Nature and in the various divisions of animal life; that there were wild men who lived in the forests, and differed from man proper principally in other than physical respects; and that there were wild men who lived in the sea: also that there were beings half-man and half-horse; others half-man and half-bird; and others, again, half-man and half-fish. In respect to the wild man of the woods, it may be said that those words are the literal signification of the Malayan words _orang outang_; and that animal's appearance seems to determine that the Satyr and kindred creatures were not entirely imaginations. For the half-man and half-horse we have abundant explanation in the various wild riding tribes of men, especially the Tartars. The half-bird appears to have been distinguished for only a singing reason, and is therefore, as it were, a piece of heraldry. For the wild man of the sea, and the half-man and half-fish, what have we?
Apparently the earliest presentation to men's eyes of that form under which the mermaid is still figured was the image, in very ancient days, of Derceto, goddess of the Philistines of Ascalon, in a temple of that city. She was woman above and fish below. She had been a beautiful virgin, but had excited that all-prevalent passion since irregulated by Aphrodite. It proved her ruin, she cast herself into the sea, and suffered the partial metamorphosis. So was it fabled in that land: but it is much more plausibly thought that the combination of woman and fish declared, hieroglyphically, some dim knowledge that those ancients had of certain relations between the moon and the sea, of which things the respective parts were typical.
Half-fishy also was the form of that Dagon which in Ashdod, or Azotus, another city of the Philistines, fell down upon his face before the ark of the Lord. This Dagon was the god, apparently, in whose honor the Philistines were gathered together on that day when blind Samson "took hold of the two middle pillars," and let down the roof, and caught so many swallows.