Hermione recited at top speed:"Golpalott's-Third-Law-states-that-the-antidote-for-a-blended-poision-will-be-equal-to-more-than-the-sum-of-the-antidotes-for-each-of-the-separate-components."
"Precisely!" beamed Slughorn. "Ten points for Gryffindor! Now, if we accept Golpalott's Third Law as true..."
"... which means, of course, that assuming we have achieved correct identification of the potion's ingredients by Scarpin's Revelaspell, our primary aim is not the relatively simple one of selecting antidotes to those ingredients in and of themselves, but to find that added component which will, by an almost alchemical process, transform these disparate elements-"
Harry Potter and the Half-blood Prince
The phrase "in and of themselves" confuses me. How should we understand it in this context?