Prophet
The idea of a "prophet" is very closely tied to the idea of the Bible itself, since the Bible was largely written by prophets. At a lower level, prophets represent people who teach from the Bible. At a higher level, they represent the Lord as He reveals himself through the Bible. Viewed in a abstract way, prophets represent the holy parts of the Bible themselves, and also represent doctrine drawn from the Bible. The reason we say "largely written by prophets" and "the holy parts of the Bible" is that not all of the books currently included in the Bible have a complete and continuous internal sense. Some -- like Job, Ruth, and Song of Solomon -- are wonderful literary pieces that got included, but which lack the systematic meanings for words and phrases. Others -- the Acts and Epistles, primarily -- are really doctrinal works, the first attempt by others to extract meaning from Jesus' life and words.
Isaiah 44:23-24
23
Sing, you heavens, for Yahweh has done it! Shout, you lower parts of the earth! Break out into singing, you mountains, O forest, all of your trees, for Yahweh has redeemed Jacob, and will glorify himself in Israel.
24
Thus says Yahweh, your Redeemer, and he who formed you from the womb: "I am Yahweh, who makes all things; who alone stretches out the heavens; who spreads out the earth by myself;