Neither can we be absolutely certain that, Socrates himself taught the immortality of the soul, which is unknown to his disciple Glaucon in the Republic; nor is there any reason to suppose that he used myths or revelations of another world as a vehicle of instruction, or that he would have banished poetry or have denounced the Greek mythology. His favorite oath is retained, and a slight mention is made of the daemonium, or internal sign, which is alluded to by Socrates as a phenomenon peculiar to himself. A real element of Socratic teaching, which is more prominent in the Republic than in any of the other Dialogues of Plato, is the use of example and illustration ('taphorhtika auto prhospherhontez'): "Let us apply the test of common instances." "You," says Adeimantus, ironically, in the sixth book, "are so unaccustomed to speak in images." And this use of examples or images, though truly Socratic in origin, is enlarged by the genius of Plato into the form of an allegory or parable, which embodies in the concrete what has been already described, or is about to be described, in the abstract. Thus the figure of the cave in Book VII is a recapitulation of the divisions of knowledge in Book VI. The composite animal in Book IX is an allegory of the parts of the soul. The noble captain and the ship and the true pilot in Book VI are a figure of the relation of the people to the philosophers in the State which has been described. Other figures, such as the dog in the second, third, and fourth books, or the marriage of the portionless maiden in the sixth book, or the drones and wasps in the eighth and ninth books, also form links of connection in long passages, or are used to recall previous discussions.