It would be nice if the proper meaning of any given text just jumped out at us, but, as Christian history, and the multiplicity of denominations, have demonstrated, the text can be interpreted in different ways. So, how do we go about trying to interpret any given text properly? Enter these three fancy terms: exegesis, eisegesis, and hermeneutics.
First: exegesis. This term comes from the Greek verb ἐξηγέομαι (exegeomai) which literally means "to lead out." In the process of exegesis, the biblical interpreter tries to lead something "out" of the text. That is, they are trying to find out what is already in the text at hand. At its most basic, one performing exegesis, also called an "exegete," is trying to find out what a text meant in its original context. An exegete must also beware not to import anything foreign into the text that was not already there.
This leads us to the second term: eisegesis. Eisegesis comes from the Greek verb εἰσηγέομαι (eisegeomai) which literally means "to lead in" and is thus the exact opposite of exegesis. Eisegesis is an interpretive vice in which a biblical interpreter (usually unknowingly) leads or brings meaning into the text that is actually foreign to the text itself. Eisegesis happens all of the time. A reader of the Bible will come to a text, and they think they already know what a text means before they have even read it carefully, and therefore they bring a foreign meaning to the text, and then they say, that is what the text means.
One way that this often happens is to bring certain meanings of words into the text. Here is one example. For many Christians, the word "gospel" has a specific meaning. The "Gospel" is the message of salvation for individual humans. Specifically, it is the message that Jesus died on the cross for the sins of the world and therefore salvation is available for those who would confess belief in Jesus. If that is the meaning of the word "gospel" for the biblical interpreter, then, when one comes upon that word in a biblical text, that definition is brought with the interpreter into the text. The problem is, that is not the meaning of the word gospel. That is one specific theological interpretation of the word, but it is not the meaning of the word as I hope the following example will show.
Let's take a look at Matthew 4:23
Jesus was going throughout all Galilee, teaching in their synagogues and proclaiming the gospel of the kingdom, and healing every kind of disease and every kind of sickness among the people. (New American Standard Version).What gospel is Jesus preaching in Matthew 4:23? Is he preaching the gospel as defined above, that Jesus died for the sins of the world? NO! He is preaching the coming of the Kingdom of God, which included the healing of sick people. You see, having a ready definition of gospel in hand and then bringing it into the text, doesn't even make sense here. Eisegesis does violence to the text by bringing in foreign concepts. It also causes people to miss the actual meaning of the text, because by importing foreign concepts, you actually miss what the text is actually saying. In the text above, you might miss that indeed Jesus did have a gospel (good news) to preach, and it was not that Jesus died for the sins of the world, but rather, it was good news about the Kingdom of God.
So, exegesis tries to get at the original meaning of a text, that is, the meaning in the original context. So, exegesis only takes us so far in biblical interpretation. It only tries to get at what a text meant. But that only answers half of the question of biblical interpretation, because any biblical interpreter is more interested in what a text means for them, here an now, than in what a text meant in its original context. We are separated from that original context by 2000 years. Is what it meant for them, necessarily what it means for me today? Maybe not. Enter our third fancy term: hermeneutics. Hermeneutics, which comes from the Greek verb ἑρμηνεύω (hermeneuo), literally means "to translate." Thus, the biblical task of hermeneutics is an attempt to translate what the text meant to what the text means for us today. Yet, one cannot even start to translate if one does not know the original.
Therefore, the primary and most important task of the biblical interpretation is exegesis, finding out what the text meant in its original context. Only then can one even begin to decipher what a text means for us, here and now.