Harry had not made an original magical discovery, but rediscovered a law so ancient that nobody knew who had first formulated it:
A potion spends that which is invested in the creation of its ingredients.
But conversely, it also says that
The fundamental principle of Potions-Making had no name and no standard phrasing, since then you might be tempted to write it down.
McGonagall and Flitwick seemed to at least be familiar with the idea, though, so there’s a good chance that you’re right.
Edit: I should probably also point out the obvious. If knowing the general rule is “WTF? Stop!” dangerous, like the professors seem to suggest it is when Harry tries it, then it’s not generally the sort of thing you’d teach your 11 year old son. There’s plenty of time to pass things like that along when the kid’s closer to adulthood and mellowed out a bit.
I got the impression it was common knowledge among powerful wizards. Am I misremembering?
If you look back at Chapter 78, it says that
Harry had not made an original magical discovery, but rediscovered a law so ancient that nobody knew who had first formulated it:
A potion spends that which is invested in the creation of its ingredients.
But conversely, it also says that
The fundamental principle of Potions-Making had no name and no standard phrasing, since then you might be tempted to write it down.
McGonagall and Flitwick seemed to at least be familiar with the idea, though, so there’s a good chance that you’re right.
Edit: I should probably also point out the obvious. If knowing the general rule is “WTF? Stop!” dangerous, like the professors seem to suggest it is when Harry tries it, then it’s not generally the sort of thing you’d teach your 11 year old son. There’s plenty of time to pass things like that along when the kid’s closer to adulthood and mellowed out a bit.