Imagine a modern recipe card unearthed by a person 1500 years in the future. The recipe is for a rice and tuna casserole. The recipe itself is only a page long. It reads:

Ingredients:
2 cups longrain white rice
2 cans tuna, drained
1 can cream of mushroom soup, etc.

Directions:
Cook the rice on the stove top with 4 cups of water. Mix with the tuna and cream of mushroom soup. Bake for 15 minutes at 250 degrees.

Now imagine in that futuristic world there is no longer such a thing as a "can," let alone cream of mushroom soup or longrain white rice. How close can that chef of the future get to replicating the original taste? The Oral Law is there to describe what is meant by each of these items. Even more than that. . .

The Oral Law would explain the concept of a can opener, possibly mentioning that there are electric versions of these instruments. It would note that the stovetop could be gas or electric, and that care should be taken not to burn oneself.

Many aspects of making a simple dish like a rice casserole are taken for granted by the author of the recipe. He/she assumes that the reader has heard of the ingredients, knows how to boil rice, that the casserole must be baked in an oven-proof container and much more. Once the person trying to follow the recipe is so far away in time and context, those assumptions of the author can no longer be held to be true.

God, rather than taking it for granted that the Jews would understand all of the Torah's laws, created the Torah with a system of interpretation designed to clarify all these issues, throughout history.

Today, without the Oral Law, we may think we know that we understand the words of the Bible, but something as simple as "rice" and "can" may have ambivalent meanings. For example, "And you shall bind them as a sign upon your eyes" scarcely translates as tefillin (phylacteries). The fulfillment of the Torah is impossible without the Oral Law.