The Blind Prophets

Homer and his guide. William-Adolphe Bouguereau

As a student assistant for Brother Cowan, a blind professor who teaches here in the Church History and Doctrine area, I was intrigued by Milton's descriptions of his own blindness and poetic opinion of his limitations.
During his invocation at the beginning of the Third Book, Milton asks that he be blessed like other blind prophet poets to be able to perceive the things of God. He lists four names: Thamyris, Maeonides, Tiresias, and Phineus. I knew a little about a few of them, but was curious to learn more about their lives and why Milton chose to allude to them.
Thamyris is described in the Iliad as being a gifted poet/singer. Unfortunately, he was so confident in his abilities that he claimed he was a greater artist than the Muses themselves. To punish him for his pride, the Muses blinded him and robbed him of his talents, making him painfully aware that all inspiration and gifts can be taken by the Gods.
Maeonides is another name for Homer, the author of the Iliad and the Odyssey. Very little is known about Homer's life. Many translations of the Greek origins of his name
suggest blindness, or that he was incapable of traveling alone and needed to be guided. There are several legends of a blind bard that are often identified as Homer, and many feel that the description of the blind bard Demodocus in the Odyssey is autobiographical. Homer is considered by many to be the greatest  of Greek poets and one that Milton would have known extremely well, as he was a master (if not creator) of the epic form.
Tiresias is a blind prophet who appears in several Greek myths, including the Odyssey and Oedipus the King. The cause of his blindness varies from myth to myth, but the most common consensus is that the Gods blinded him as punishment for revealing their secrets. He often acts as an intermediary, a concept that could appeal to Milton as he attempts to "justify the ways of God to men." Unlike Milton, however, Tiresias' prophecies are frequently morbid, and he is often hesitant to disclose them.
Phineus was a king who also bore the gift of prophecy. He is mentioned in the tales of the Argonauts' voyage, and that account of his blindness is most trusted. According to that tale, he was, similar Tiresias, blinded for revealing the future to mankind. He was also punished that whenever he sat down to eat, harpies would fly down and steal his food. Jason and his Argonauts aided Phineus in taking care of the harpies, for which he guided them through the treacherous Sympleglades.
In researching each of these referenced men, I didn't come across a strong unifying bond that I felt Milton was trying to allude to. I think it was a simple combination of their blindness and prophetic/poetic abilities that he hoped to be blessed with as he sought to create his epic poem.