SARAH: Normally, we use relative in contrast to absolute — something that is relative depends on the relative point of view, where as something absolute is true no matter what, independent of a particular viewpoint or context.

RALPH: This can't be what Hamlet means here — he's looking for more certain grounds, or proof, about Claudius's guilt — he doesn't want relative proof, he wants more absolute proof.

SARAH: But in fact, that's closer to what Shakespeare actually means by the term — here the word means relevant or pertinent.

RALPH: And if Claudius shows signs of his own guilt, this is more relevant or more substantial proof than if he's accused of a crime by a mysterious ghost.