Why did Milo recieve an unusual package?

At the beginning of The Phantom Tollbooth, Milo is describing his today. The reader learns that Milo is bored throughout his entire day. When he is at school, he is thinking about being at home and when he is at home, he is thinking about being at school. No matter what Milo is doing, it is does not seem to occupy him.
On this particular day, Milo gets home and finds a package that has a bright blue envelope next to it. The letter in the envelope reads, "FOR MILO, WHO HAS PLENTY OF TIME." When he opens the package, Milo discovers the phantom tollbooth and begins to assemble it. He starts his toy car and drives through the tollbooth, for he has nothing better to do.
At this point we don't know who sent the package and we don't know why it was sent but we can infer that Milo is going to learn something about time from the letter that was attached to the package. As Milo adventures through the Land's Beyond, he meets a variety of characters who teach him various lessons about the importance of using your time instead of wasting it.

In The Phantom Tollbooth, the main character is a young boy by the name of Milo. Milo's perennially bored and doesn't find anything in life remotely interesting. He especially hates learning; he thinks that seeking knowledge is the biggest waste of time there is.
All that changes, however, when Milo receives a mysterious package one day. Next to the package is a bright blue envelope, which reads "FOR MILO, WHO HAS PLENTY OF TIME." Inside the package, of course, is the phantom tollbooth of the book's title. Once he's assembled the tollbooth, Milo's going to rev up his toy car and drive straight through it down the highway to Dictionopolis. Milo's received the package—we don't know exactly who sent it—because someone in a strange, far away land has decided that he needs to be shown the way to the Kingdom of Wisdom. And we might readily agree that someone who finds seeking knowledge a waste of time is desperately in need of whatever wisdom this distant land can bestow.