Don Quixote attacking windmills

When Don Quixote mistakes windmills for giants, he famously attacks them. Spoiler alert: he loses. Hence the origin of the phrase "tilting at windmills,” which means attacking imaginary enemies while wasting time and resources. Declan thinks about this while deciding if the Clypeate is too amazing to be true, and Bruce also references the windmills when he’s about to drop gut-wrenching revelations on Declan.