Course Hero. "The Wonderful Wizard of Oz Study Guide." Course Hero. 27 Oct. 2016. Web. 27 Apr. 2017. <https://www.coursehero.com/lit/The-Wonderful-Wizard-of-Oz/>.
Course Hero. (2016, October 27). The Wonderful Wizard of Oz Study Guide. In Course Hero. Retrieved April 27, 2017, from https://www.coursehero.com/lit/The-Wonderful-Wizard-of-Oz/
(Course Hero, 2016)
Course Hero. "The Wonderful Wizard of Oz Study Guide." October 27, 2016. Accessed April 27, 2017. https://www.coursehero.com/lit/The-Wonderful-Wizard-of-Oz/.
Course Hero, "The Wonderful Wizard of Oz Study Guide," October 27, 2016, accessed April 27, 2017, https://www.coursehero.com/lit/The-Wonderful-Wizard-of-Oz/.
The cyclone that takes Dorothy out of her own world is a symbol of the powerful and irresistible pull toward the unknown. When the book opens all Dorothy knows is the flat, dry world around her. The cyclone pulls her and Toto into a realm she couldn't possibly have imagined. This is not to say that Dorothy fully accepts or appreciates her new world! But she can only recognize the value of her known universe by being plunged into an unknown one.
The Emerald City is not as green as its name suggests. Oz requires all his citizens, even the animals, to wear green-lensed eyeglasses so their surroundings appear totally green.
Why green? Some critics have suggested the color is meant to symbolize American currency, but there are many reasons for suspecting that interpretation to be far-fetched. It's just as likely Baum chose green for Oz's capital city because it lies between the blue land of the Munchkins and the yellow land of the Winkies. It could also be possible Baum simply liked the color green; emeralds were his birthstone.
The point is not the color of the spectacles but the fact that they cause Oz's subjects to see what he wants them to see. The Guardian of the Gate tells Dorothy if she did not wear them, "the brightness and glory of the Emerald City would blind you." More likely the eyeglasses make the Emerald City look more impressive and thus cause Oz to seem even more powerful.
Once the green spectacles have been locked on, they can't be removed until a visitor leaves the Emerald City. Oz is imposing an imaginary landscape on his subjects—but Baum never suggests that anyone complains. The human ability to filter out the truth can be both active and passive.
The expression that someone is full of hot air means their speech is more impressive than their actions could possibly be. By the time Oz takes off in his balloon, it has become manifestly obvious that he's full of hot air himself. He's not a Wizard. He has no magic powers; he only knows how to create special effects.
The Wizard is an authority figure whose authority is entirely fictitious. Even after he's been exposed as a charlatan, he continues to trick his subjects. He doesn't even know how to build the balloon correctly; because he leaves out a landing apparatus he floats helplessly into the sky. At that point it becomes obvious to the reader (if not quite to Dorothy) that not all authority figures are reliable.