In the Edolas arc, earth land wizards can't use magic because it's limited. I understand all the reasons behind that ect.
But why can't Natsu generate his own magic from eating flames? It's shown him eating the flame of a torch before they enter the cave/mine tunnel, but he still can't generate magic. It didn't explain why that was!
If natsu was able to generate magic by eating fire then they also should've still had the magic that they had stored up before going to Edolas because later they explain that mages actually don't produce their own magic they have 2 "origins" that store magic that they collect from around them. I think that similar to a vacuum the atmosphere in Edolas sucked the magic they had stored out of their origins and any magic he got from eating the fire would be as well and since there is no magic around their origins can't collect magic. This is all speculation mind you none of this is in the manga or anime as far as i know as an explanation for the Edolas arc's magic use however if this is the reason then the pills would act as a way to hold magic i think. like a lacrima
Natsu already had plenty of power but he lacked the ability to contort it into spells.
There was no actual loss of magic power. This is shown by the fact that wizards without the ability to cast (pre-xball) had magic energy to be stolen by the kingdom. Edolas is another world with different laws of nature that likely affect the mechanism for using magic. This is also represented by the strange taste of air and iron in Edolas. They are clearly made of similar or identical materials but are strange tasting in Edolas which shows the earth land mechanism of magic on the fritz. It should be noted that passive magic was still active: immense strength, fire immunity, and enhanced senses. There must be an adjustment of some type to begin controlling magic in Edolas. Xballs likely corrected the flaw in the casting mechanism either chemically or some magic equivalent. The friendly exceeds adjusted within their own minds to the new environment.
There was ether nano in Edolas but since there were no high caliber casters to absorb it and transfer the power to lacrima the only magic power the Edolas people could use was magic that had become condensed in the earth naturally. Somewhat similar to fossil fuels(hint hint).
Because he needs magic to turn those flames into his own power. Eating flames is similiar to us eating food, we don't need magic to eat, but using food food as a weapon against enemies?
Natsu needs to convert those flames into his own to use it.
Here is an idea: Natsu's home world is overflowing with magic. Maybe flames and more generally every object there has magic inside it from the very beginning. This would explain why, as user30104 mentioned, magicians can collect magic from their surroundings. By his upbringing as a Dragon Slayer, he can eat fire insofar that he directly absorbs all magic left in it.
In conclusion, in the almost magicless Edoras, there is no intrinsic magic in any object, yet alone flames, so Natsu couldn't just use fire as free magical batteries there.
It should also be noticed that Natsu's power increases a lot during the course of the manga and the little bit of magic that he can gain by eating flames may be enough to beat up some thugs, but not enough for the threads of Edolas and later.
