Well, I also agree that the consummately wise Moses confessedly indicates by the prohibition before us, that we must not resemble these animals; but I do not assent to the explanation of what has been symbolically spoken. For nature never can be forced to change. What once has been impressed on it, may not be transformed into the opposite by passion. For passion is not nature, and passion is wont to deface the form, not to cast it into a new shape. Though many birds are said to change with the seasons, both in colour and voice, as the blackbird (κόσσυφος), which becomes yellow from black, and a chatterer from a singing-bird. Similarly also the nightingale changes by turns both its colour and note. But they do not alter their nature itself, so as in the transformation to become female from male. But the new crop of feathers, like new clothes, produces a kind of colouring of the feathers, and a little after it evaporates in the rigour of winter, as a flower when its colour fades. And in like manner the voice itself, injured by the cold, is enfeebled. For, in consequence of the outer skin being thickened by the surrounding air, the arteries about the neck being compressed and filled, press hard on the breath; which being very much confined, emits a stifled sound. When, again, the breath is assimilated to the surrounding air and relaxed in spring, it is freed from its confined condition, and is carried through the dilated, though till then obstructed arteries, it warbles no longer a dying melody, but now gives forth a shrill note; and the voice flows wide, and spring now becomes the song of the voice of birds.