The Phantom Tollbooth is structured as an allegory, a literary form that was popular in the Middle Ages. As such, it has a relationship with Pilgrim's Progress, a religious Christian allegory written in 1678 and extremely popular and well-read in its time. As Emily Maxwell wrote in her 1961 review of The Phantom Tollbooth: "As Pilgrim's Progress is concerned with the awakening of the sluggardly spirit, The Phantom Tollbooth is concerned with the awakening of the lazy mind."
The Phantom Tollbooth also has a strong relationship to other adventure novels where a character journeys through a fantastical world and comes out transformed on the other side. Gulliver's Travels is a good...
