How to understand “in and of themselves” in this context

Question

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?

Answer 1

The simplest alternative to "in and of themselves" in this case would be "only", though its not a perfect fit.

It's a slightly awkward, and slightly old-fashioned idiom, and can be compared with "the sum of [its] parts being greater than the whole." Specifically, the speaker is saying that an antidote for one ingredient (or all of them) won't necessarily be an antidote for the combination.

Think of it like a cake - if you dropped an egg on the floor, you would clean it up one way. If you dropped flour, you would clean it up differently, but if you dropped a cake, neither method of cleaning would be appropriate "in and of itself".