Answer:
In this passage, we can notice that the Dursleys' hate magic and everything that cannot be considered as "normal", as we can see from the following example:
<em>Ever since Harry had come home for the summer holidays, Uncle Vernon had been treating him like a bomb that might go off at any moment, because Harry Potter wasn’t a normal boy.
</em>
For them, Harry's magical powers represent an abnormality which they are trying to eradicate. They are ashamed of Harry's gift, and they are doing everything they can in order to hide him from their friends, neighbors, and acquaintances. According to the Dursleys' Harry is not normal because he is a wizard and the only thing they hate more than Harry is magic:
<em>As a matter of fact, he was as not normal as it is possible to be. Harry Potter was a wizard.
</em>
On the other hand, Harry feels very lonely, he misses Hogwarts, his friends, the fact he could use magic there, and all those things which were not normal for the Dursleys':
<em>He missed Hogwarts so much it was like having a constant stomachache. He missed the castle, with its secret passageways and ghosts, his classes, the mail arriving by owl, eating banquets in the Great Hall, sleeping in his four-poster bed in the tower dormitory, visiting the gamekeeper, Hagrid, in his cabin next to the Forbidden Forest in the grounds, and especially, Quidditch, the most popular sport in the wizarding world.
</em>
For Harry, magic is his past, his future, the only thing which makes him happy and reminds him of his parents. These "abnormalities" are part of his life and he could not imagine spending the rest of his life with the Dursleys', without being able to use magic again.
