Lu'cifer. (light-bearer). Found in Isaiah 14:12 coupled with the epithet "son of the morning", clearly signifies a "bright star", and probably what we call the morning star. In this passage, it is a symbolical representation of the king of Babylon, in his splendor and in his fall.
Its application, from St. Jerome downward, to Satan in his fall from heaven, arises probably from the fact that the Babylonian empire is, in Scripture, represented as the type of tyrannical and self idolizing power, and especially connected with the empire of the Evil One in the Apocalypse.