I think the most powerful theses are those that can point out that discoveries can facilitate a fresh/renewed understanding of the world and people because it's a broad and versatile statement
With this point in mind, also mention the texts that you are writing about, and then find a key relationship between all of the texts
So collectively, what do all of your texts illustrate about discovery?
Also consider the nature of discovery -> is it physical, emotional, philosophical/intellectual?
AND what impact does it have on both the persona or society or even the audience?