[Giving him a flat stare, no get back here we're not done yet--]

It has everything to do with the end result. Means aren't magically provided, they're established through experimentation and are essential for reaching any form of conclusion - whether thatbe 'this is the extent of the subject's limit', or 'the subject cannot be killed'.

[...Hmm

are there any open windows in here

because that sure felt remarkably chilly for a second there...]