2.  The Historical theory; according to which all the persons mentioned in mythology were once real human beings, and the legends and fabulous traditions relating to them are merely the additions and embellishments of later times.  Thus the story of Aeolus, the king and god of the winds, is supposed to have risen from the fact that Aeolus was the ruler of some islands in the Tyrrhenian Sea, where he reigned as a just and pious king, and taught the natives the use of sails for ships, and how to tell from the signs of the atmosphere the changes of the weather and the winds.  Cadmus, who, the legend says, sowed the earth with dragon’s teeth, from which sprang a crop of armed men, was in fact an emigrant from Phoenicia, and brought with him into Greece the knowledge of the letters of the alphabet, which he taught to the natives.  From these rudiments of learning sprung civilization, which the poets have always been prone to describe as a deterioration of man’s first estate, the Golden Age of innocence and simplicity.

3.  The Allegorical theory supposes that all the myths of the ancients were allegorical and symbolical, and contained some moral, religious, or philosophical truth or historical fact, under the form of an allegory, but came in process of time to be understood literally.  Thus Saturn, who devours his own children, is the same power whom the Greeks called Cronos (Time), which may truly be said to destroy whatever it has brought into existence.  The story of Io is interpreted in a similar manner.  Io is the moon, and Argus the starry sky, which, as it were, keeps sleepless watch over her.  The fabulous wanderings of Io represent the continual revolutions of the moon, which also suggested to Milton the same idea.

   “To behold the wandering moon
    Riding near her highest noon,
    Like one that had been led astray
    In the heaven’s wide, pathless way.”

    —­Il Penseroso.

4.  The Physical theory; according to which the elements of air, fire, and water were originally the objects of religious adoration, and the principal deities were personifications of the powers of nature.  The transition was easy from a personification of the elements to the notion of supernatural beings presiding over and governing the different objects of nature.  The Greeks, whose imagination was lively, peopled all nature with invisible beings, and supposed that every object, from the sun and sea to the smallest fountain and rivulet, was under the care of some particular divinity.  Wordsworth, in his “Excursion,” has beautifully developed this view of Grecian mythology: 

   “In that fair clime the lonely herdsman, stretched
    On the soft grass through half a summer’s day,
    With music lulled his indolent repose;
    And, in some fit of weariness, if he,
    When his own breath was silent, chanced to hear
    A distant strain far sweeter than the sounds
    Which his poor skill could