When, therefore, the Serpent pushes forward the ribs, the edges of the scaly belts will catch against the slightest projection, and are able to give a very powerful impetus to the body. It is scarcely possible to drag a snake backwards over rough ground; while on a smooth surface, such as glass, the Serpent would be totally unable to proceed. This, however, was not likely to have been studied by the ancient Hebrews, who were among the most unobservant of mankind with regard to details of natural history: it is, therefore, no wonder that the gliding of the Serpent should strike the writer of the proverb in question as a mystery which he could not explain. The poisonous nature of some of the Serpents is mentioned in several passages of Scripture; and it will be seen that the ancient Hebrews, like many modern Europeans, believed that the poison lay in the forked tongue. See, for example, Ps. lviii. 4: "Their poison is like the poison of a serpent" (_nâchâsh_). Also Prov. xxiii. 32, in which the sacred writer says of wine that it brings woe, sorrow, contentions, wounds without cause, redness of eyes, and that "at the last it biteth like a serpent, and stingeth like an adder." [Illustration: COBRA AND CERASTES, THE ASP AND ADDER OF SCRIPTURE.] The idea that the poison of the Serpent lies in the tongue is seen in several passages of Scripture. "They have sharpened their tongues like a serpent; adders' poison is under their lips" (Ps. cxl. 3). Also in Job xx. 16, the sacred writer says of the hypocrite, that "he shall suck the poison of asps: the viper's tongue shall slay him." As to the fiery Serpents of the wilderness, it is scarcely needful to mention that the epithet of "fiery" does not signify that the Serpents in question produced real fire from their mouths, but that allusion is made to the power and virulence of their poison, and to the pain caused by their bite. We ourselves naturally employ a similar metaphor, and speak of a "burning pain," of a "fiery trial," of "hot anger," and the like. [Illustration: THE ISRAELITES ARE BITTEN BY SERPENTS IN THE WILDERNESS, AND MOSES LIFTS UP THE SERPENT OF BRASS.] The epithet of "flying" which is applied to these Serpents is explained by the earlier commentators as having reference to a Serpent which they called the Dart Snake, and which they believed to lie in wait for men and to spring at them from a distance. They thought that this snake hid itself either in hollows of the ground or in trees, and sprang through the air for thirty feet upon any man or beast that happened to pass by. * * * * * We will now take the various species of Serpents mentioned in the Bible, as nearly as they can be identified. Of one species there is no doubt whatever. This is the Cobra di Capello, a serpent which is evidently signified by the Hebrew word _pethen_.