In Mishlei it says, ‘[The Torah] is more precious than pearls, and all your possessions cannot compare to it’. This verse requires explanation, for how can it compare the Torah, that is ultimate spirituality and was Hashem’s ‘toy’ before He created the world, to inanimate pearls that are less developed than vegetation or animals.
The reason is that what makes pearls more expensive than other things is their scarcity, as all precious metals and stones are priced largely by how rare they are. Similarly, after a person dies, he cannot acquire one iota of Torah he did not learn to some degree in this world. Although a person’s understanding in the next world is incomparably deeper than his understanding in this world, this is true only of things that he learned already and did not perceive their depth, but things he did not learn at all will be out of his reach forever and ever.