I have a bunch of favorite West Wing episodes, but this one comes to mind--Season 3, Episode 16: Dead Irish Poets.
Sam's former professor is dying and comes to DC to advocate for the superconducting supercollider. A key Senator is blocking the funding of the super-conducting super-collider.
Just before the dialog below, Sam and the Senator have a rough conversation and the Senator walks out, but Sam calls him back, apologizing and appealing to him.
Senator: "If we could only describe what benefit it has--no one's been able to do that"
Professor: "That's because great achievement has no roadmap. But the Xray's pretty good. So is penicillin, but neither were discovered with a practical objective in mind. And when the electron was discovered in 1897 it was useless. Now we have an entire world run by electronics. Haydn and Mozart never studied the classics. They couldn't--they invented them. "
Sam: "It's discovery."
Sam: "That's the thing you were...discovery is what.That's what this is used for. It's for discovery."
The rest of the storyline is pretty great too.