He'd always been frightened of ending up as one of those child prodigies that never amounted to anything and spent the rest of their lives boasting about how cool they'd been at age ten. But then most adult geniuses never amounted to anything either. There were probably like a thousand people as intelligent as Einstein for every actual Einstein in history. Because they hadn't gotten their hands on the one thing you absolutely needed to achieve greatness. They'd never found an important problem.
You're mine now, Harry thought at the walls of Diagon Alley, and all the shops and items, and all the shopkeepers and customers; and all the lands and people of wizarding Britain, and all the wider wizarding world; and the entire greater universe of which Muggle scientists understood so much less than they believed. I, Harry James Potter-Evans-Verres, do now claim this territory in the name of Science.
Lightning and thunder completely failed to flash and boom in the cloudless skies.
"What are you smiling about?" inquired McGonagall, warily and wearily.
"I'm wondering if there's a spell to make lightning flash in the background whenever I make an ominous resolution," explained Harry. He was carefully memorizing the exact words of his ominous resolution so that future history books would get it right.
"I have a distant feeling that I ought to be doing something about this," sighed McGonagall.
"Ignore it, it'll go away. Ooh, shiny!" Harry put his thoughts of world conquest temporarily on hold and skipped over to a shop with an open display, and Professor McGonagall followed.