Hermeneutics is the scholarly term for rules of Biblical interpretation. The Talmud records several methodologies. One is the Seven Rules of Hillel. These were later expanded by Rabbi Yishmael into thirteen rules (or Middot). These are actually recited in the morning prayers. Rabbi Akiva had a totally different methodology, based on extra or missing words or letters, the use of inclusive words (like "and" or "with") and limiting words (like "but" or "only"). Both methods were employed in the Talmud. Another set of thirty two rules was presented by Rabbi Eliezer ben Rabbi Yosi Hagalili. These later rules were intended not for halachic (legal) exposition, but for aggadic (homiletic, metaphorical) interpretation.
Why bother? Why not just take the text literally? Allow me to pose the following question. Where does the Torah (or any Biblical book) forbid sexual relations between a father and daughter? IT DOESN'T!.Among the incestuous relationships forbidden by the Torah, some blood relatives and some not, we search in vain for what would seem to be a most basic abomination! However, the Talmud points out that we DO find a prohibition of relations with a granddaughter. We have here an argument called "kal V'chomer" (from the minor towards the major). If a granddaughter is forbidden, how much more so a daughter! Is this rabbinic law? NO! It is seen as Biblical; validly derived by the rules that have been handed down to us. (There were, in fact, some views outside the rabbinic tradition that DID allow such a union. See 1 Corinthians 7:36).
But why wouldn't the Torah specify ideas like this? The Torah is a Divine document, far beyond human comprehension, with layers of meaning that remain yet to be discovered. It was revealed with explanation, guidelines, hints to be used in interpretation. There is no extraneous letter. It is written tersely, yet it contains every imaginable (and many beyond imagination) secret and mystery.
I like to think of this as analogous to romantic love. No one EVER really knows another person. In fact, we don't really know ourselves! Yet, when we have known someone for a relatively short time, we may realize that we love them. If it is a good relationship, love matures and grows. Even after several decades, we discover aspects of the other person that make us love them even more! We realize ho without that person, how dark our lives would have been! So it is with the Torah. As children, we sit wide-eyed at the telling of story of the Great Flood, the Exodus, the splitting of the Sea. As we mature and continue studying, we get to know the Torah better. Each story has lessons vital FOR ME! And as we encounter new challenges in life, the Torah provides new answers! We love the Torah when we are children, but love her so much more by the time we have weathered numerous life challenges. We realize that G-d's teachings and guidance are so intricately woven, that each thread tells us exactly what we need, that we may well have overlooked while examining the entire fabric.
I noted above that the thirteen rules of interpretation are in our daily prayers. Why would they be in a prayer? The Kabbalists inform us that these thirteen Torah rules are inextricably bound up with the Thirteen Attributes (also called Middot!) with which we implore G-d's Mercy. If we are studying the Torah correctly, it becomes a prayer. If we pray correctly, finding G-d in all the ups and downs of life, prayer opens up the Torah for us in a new way. Prayer can be the ultimate Torah study! The Zohar says that if the Torah was only what we read on the surface, we could write a much better Torah. But that is NOT the Torah. There are in and outs, permutations, like a great poem combined with the most personal prayerful devotion, that grows as we grow, and offers ever widening vistas.