From the current issue of The Jewish Week (link):
There are many passages in Jewish literature that have no immediate application. Numerous laws have long since passed out of use along with situations that are no longer relevant or even possible. But serious students of Judaism still pore over these texts and feel enriched. How can that be? In Judaism this is called studying “lishma” for no purpose other than the mitzvah of studying Torah. As Rabbi A.J. Heschel poetically explains:While I disagree with the seeming (probably unintended) equation of Torah with all other knowledge, I think the sentiment in general is well said.“What is nobler than the unpractical spirit? The soul is sustained by the regard for that which transcends all immediate purposes. ... The world is sustained by unworldliness.”How straitened and sad is a world in which people study only that which they can use, as if life were a trade school writ large. “Read at whim!” cried the critic Randall Jarrell. Study that which will have no use; learn things for the simple sake of knowing. Let creation unfold before you in all its array.
When physicist Robert Wilson was asked at a congressional hearing whether the Fermilab particle accelerator would contribute to national security, he said: “It has nothing to do with defending our country except to make it worth defending.” All knowledge is a gift from the ultimate Source and is to be cherished.