On Harry's Arrival at the Dursley's:
"Yes," said Professor McGonagall. "And I don't suppose you're going to tell me why you're here, of all places?"
"I've come to bring Harry to his aunt and uncle. They're the only family he has left now."
"You don't mean - you can't mean the people who live here?" cried Professor McGonagall, jumping to her feet and pointing at number four. "Dumbledore - you can't. I've been watching them all day. You couldn't find two people who are less like us. And they've got this son - I saw him kicking his mother all the way up the street, screaming for sweets. Harry Potter come and live here!"
"It's the best place for him," said Dumbledore firmly. "His aunt and uncle will be able to explain everything to him when he's older. I've written them a letter."
"A letter?" repeated Professor McGonagall faintly, sitting back down on the wall. "Really, Dumbledore, you think you can explain all this in a letter? These people will never understand him! He'll be famous - a legend - I wouldn't be surprised if today was known as Harry Potter day in the future - there will be books written about Harry - every child in our world will know his name!"
"Exactly," said Dumbledore, looking very seriously over the top of his half-moon glasses. "It would be enough to turn any boy's head. Famous before he can walk and talk! Famous for something he won't even remember! Can't you see how much better off he'll be, growing up away from all that until he's ready to take it?"
Professor McGonagall opened her mouth, changed her mind, swallowed, and then said, "Yes - yes, you're right, of course."
Book 1 p7
On Harry's Accidental Magic
Harry had a number of instances of accidental magic before he went to Hogwarts.
The following incidents were mentioned or described in Book 1 Chapter 2 "The Vanishing Glass":
- growing back his hair overnight after Aunt Petunia cut most of it off.
- making Dudley's old ugly jumper shrink when Aunt Petunia was trying to put it on Harry
- apparating to the roof on the school kitchens when trying to get away from Dudley's gang
- vanishing the glass in front of the boa-constrictor's tank at the zoo (and speaking to the snake, though that wasn't exactly "accidental").
In "The Sorting Hat" another incident is mentioned:
- turning his teacher's wig blue.