Final answer:
Teiresias's lack of external sight suggests a metaphorical inner vision and a deeper insight into truths unseen by those with physical sight, symbolic of spiritual insight and the contrast to Oedipus's literal sight which is blind to his fate.
Step-by-step explanation:
Teiresias's lack of external sight in literature often suggests a metaphorical inner vision or insight. In the context of his argument with Oedipus, Teiresias's blindness conveys his ability to see truths that are not visible to those with physical sight.
Paradoxically, while Oedipus accuses Teiresias of being blind, it is actually Oedipus who is metaphorically blind to the truth about his own life.
This motif aligns with the idea presented by Socrates in Plato's dialogues that true vision or enlightenment comes from intellectual and philosophical insight rather than the mere physical ability to see.
In the case of Teiresias, his blindness underscores his role as a prophet who, unencumbered by the distractions of the physical world, can access a higher level of knowledge and truth.
This is similar to the prisoners in Socrates's allegory of the cave, who mistake shadows for reality and the enlightened individual who, upon seeing the light of truth, finds it difficult to operate in the dimly lit world of those still ensnared by illusions.
Thus, Teiresias's blindness can be seen as an illustration of spiritual insight contrasted against Oedipus's literal sight that is ultimately blind to his own fate and identity until the tragic revelation.