Following are some notes from my reading. They serve to illustrate a few of the many interpretations of the story.
Interesting analysis of the characterization
http://www.bridgewater.edu/philo/philo96/knott.html
This article states that the Wizard is a parable of the populast movement.
http://www.u.arizona.edu/~marcum/wizard1.htm
“One particular reviewer took that theme to the next level and wrote an essay that would become what most historians accept as the correct interpretation of The Wizard of OZ. In 1964 high school history instructor Henry M. Littlefield published a paper in American Quarterly that analyzed the social phenomenon in 19th century America among the agricultural and labor force spheres known as ‘populism’ and analogized it with the Wizard of OZ. The Wizard of OZ: Parable on Populism was an investigation into what extent Baum’s work was a biography of William Jennings Bryant and the populist movement. Littlefield’s paper was written as an analysis of the political life and times of L. Frank Baum and his peers. However, like all creative thinkers, Baum was influenced by the social constructs, restraints, and developments of his era. Considering this notion, the purpose of this paper is to explain how the Wizard of OZ is an autobiography, as well as ethnology of 1890’s Americana.”
WOW: many of Baum’s publications on line!!!!
http://www.lib.umd.edu/ETC/ReadingRoom/Fiction/Baum/
One of the more interesting assessments of the story:
http://www.nonduality.com/oz.htm
“I believe that the perennial popularity (and classic film status) of the Wizard of Oz is due to the fact that it helps explain a way to resolve that "inner longing" that all people have for True Self. Through the use of symbolism, it clearly shows the futility of the search, and the constant presence of That which is desired -- whether or not we are aware it is there. It contains an uplifting message that is also a true one, and people subconsciously respond to that (especially children, who are generally closer to Ground of Being than adults).”
One more note on Toto: I think he also represented the "still, small voice" of the Infinite within each of us. Toto was a complex character. Perhaps he represented the Infinite Itself. Toto is the mystery, Dorothy's spirit and will to go on. When the old lady took Toto away, it also took Dorothy's spirit and happiness away, and precipitated the dark night of the soul period which resulted in her "traveling to the land of Oz." Toto is the aspect of unconditional love, that aspect that is exquisitely vulnerable and yet at the same time represents pure intuition and guidance and strength, both for "itself" and for its "owner." Remember that Toto was smart enough to jump out of the old lady's basket and escape, yet Dorothy was unaware of the fact. Toto also "saved" Dorothy several times throughout the movie, if I remember correctly. Essentially, Toto represents intuition and love.