Anybody who's read enough fantasy novels knows that there's Tolkien and then there's the writers who react to Tolkien. Maybe some of the latter category are better than Tolkien at some things, but Tolkien was a founding father to the entire genre in a way no one else was, or ever will be. One of the biggest rifts between Tolkien and his followers are in how they treat prophecy. His followers (and I include J.K. Rowling in this) make prophecies into some kind of message from the future that is vague enough to be applied to lots of different things, usually in a self-fulfilling or completely obscure manner, till some previously unknown bit of info is revealed. Prophecies, to be honest, aren't much help in most fantasy novels except in hindsight. They serve to give a puzzle and a mystery and maybe at best a philosophical point about fate vs. free will (the prophecy in Tad Williams' Memory Sorrow and Thorn is one of my favorites, but I still categorize it as "not the way prophecy really works").
Contrast this with Galadriel's mirror. It's different -- images instead of words, not just predicting the future but mingling it with the past and present. The main event in Tolkien with the ring is there but strangely subsumed by other events such as the Scouring of the Shire. It's poetry and juxtaposition, pain and healing, and it shows not some key to the future but a deep insight into how the world works. This is prophecy the way the Bible does it.
Here's what I mean. Take the famous Immanuel prophecy in Isaiah 7. To the doubting King Ahaz, Isaiah says, "the Lord Himself will give you a sign: Behold, the [young woman] shall conceive and bear a Son, and shall call His name Immanuel ['God-With-Us']. ... before the Child shall know to refuse the evil and choose the good, the land that you dread will be forsaken by both her kings. The Lord will bring the king of Assyria upon you and your people and your father’s house ..." The child is more an adverb than a noun here; he is a timer, a sign of immanence that things will happen soon.
Some people find this problematic because the Hebrew text uses the word for "young woman" and the word "virgin" is used in the Greek translation only. Matthew quotes the Greek (and presumably secondary) version when he says that Jesus fulfills this promise. Isn't Matthew stretching the case and reading something that wasn't originally there? It would be if the prophecy was a legal word-for-word prediction. But it's more than that. To see how, you just have to read the next 2 chapters of Isaiah.
Isaiah 8 has an echo of Isaiah 7, when it reads "Then I went to the prophetess, and she conceived and bore a son. Then the Lord said to me, “Call his name Maher-Shalal-Hash-Baz; for before the child shall have knowledge to cry ‘My father’ and ‘My mother,’ the riches of Damascus and the spoil of Samaria will be taken away before the king of Assyria.” " Again, a timer, a sign of immanence, and an omen that judgment is near. That, in a very real sense, God is with us. The only real difference here is the name of the child. Later in the chapter Isaiah reiterates that the point of these signs is that God should be trusted more than political alliances or pseudo-scientific soothsayers: "Here am I and the children whom the Lord has given me! We are for signs and wonders in Israel from the Lord of hosts, who dwells in Mount Zion."
And then Isaiah 9 ups the ante, to say the least. Read it in the light of the two previous signs: "For unto us a child is born, unto us a Son is given; and the government will be upon his shoulder. And his name will be called Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace. Of the increase of His government and peace there will be no end, upon the throne of David and over His kingdom, to order it and establish it with judgment and justice from that time forward, even forever." You thought those other passages were prophecies? Now, this is a prophecy. But it is enhanced because it is part of a pattern: a child is promised, the child comes as a sign that God is with us, that despite appearances He's doing what He said. And this child really means, literally, God is with us, because he is God.
When you look at the three prophecies together it becomes clear that this is the way God likes to work. He gives life miraculously (every conception a miracle); He nurtures and sustains that life; and He uses that life to show everyone that He is here, with us. He does this all the time, but in these three cases He did it with specific names, to specifically show Himself. The pattern of the prophecies is as important as the details, and they are poetic repetitions, with the third a case of glorious hyperbole. He did the first two, and He promises the third.
Hundreds of years pass, and then one night the angel Gabriel tells Mary that she will have a son, though she is a virgin, the son of God (a term used for kings like David in the OT, another similarity to Isaiah's kingly prophecies). Yeah, she's a "young woman," too, but the virgin part shows God's power to an extreme extent -- just like the Isaiah 9 prophecy shows God's intentions to use his power to an extreme extent. Matthew is saying that Jesus fulfills Isaiah's prophecy in a way consistent not just with Isaiah 7 but also 8 and 9, and to an extent that may have been inconceivable (is that a pun?) even to Isaiah. Isaiah is showing the way God works, not once, but three times, and it is fulfilled in Immanuel, and in the second kid (don't want to type out that name), but most fully in Jesus, just like the promises are made most fully the third time. The prophecies that apply to Jesus run throughout Isaiah like a river, and they all came true at once. That's why Matthew's so flabbergasted at it all. I think he counts on us reading past Isaiah 7 to get to 8 and 9 to see the whole picture here. We're missing the point by reading out of context.
The Resurrection is like that too, a combination of a huge web of prophecies made even more true by the combination. It is the miracle of miracles, a re-creation by the creator in the middle of time, and the fulfillment of a whole slew of prophecies about how God gives life when we can do nothing else for ourselves. The three days thing from Hosea, the promise of removing the veil of death from the nations in Isaiah 25, the "sparks" verse in Daniel, the "sign of Jonah" as quoted by Jesus himself, they all came true at once. The ultimate in futility and injustice is death; God showed his power and justice in reversing it. It's entirely consistent with the way He works, and with passages His spirit inspired throughout the 17 prophets, in the Torah, and beyond.
Here's the point: it's not about the prophecies, it's about the faithfulness of God. Even prophecies can turn into idols if we focus on them. God gives us more than we expected in a way we did not anticipate. It's bot about proving the prophecies or even the prophecies proving God. It's about the God-with-us proving his character through the prophecies, altogether and all at once. Jesus trusted God through death and beyond, the God revealed in the prophecies, but the prophecies are just words without God. A true prophecy is known by its fruit: the true prophecy itself fades away because it is eclipsed by the incredible steadfastness and faithfulness of the God who made it.
[For more thoughts on how prophecy works in Isaiah, see this post.]