Homer becomes depressed after learning he has lived past the halfway point of the average life expectancy for men, without accomplishing anything worthwhile. The Simpson family try to cheer him up by showing him a film of his accomplishments and a special appearance by the character KITT from the Knight Rider television series that Homer is a fan of. When the film projector stops working, Lisa mentions that Thomas Edison invented the projector and many other inventions. Homer decides to learn more about Edison and eventually idolizes him. In an attempt to follow his footsteps, he quits his job at the Springfield Nuclear Power Plant to become an inventor.

The family disapproves of his first few inventions, including a make-up shotgun, electric hammer, alarm that only stops beeping when something is wrong, and reclining chair with a built-in toilet, making Homer more depressed. However, they like one particular invention, a chair with two hinged legs on the back, making it impossible to tip over backwards. Homer is encouraged until he notices his poster of Edison shows him sitting in the same type of chair. Bart points out that the chair is not featured on a list of Edison's inventions, meaning he never told anyone of this invention.

Homer and Bart travel to the Edison Museum in Llewellyn Park, New Jersey, with his electric hammer to destroy the chair, but Homer notices a poster of Edison comparing himself to Leonardo da Vinci, much like how Homer compared himself to Edison. Feeling a renewed connection to Edison, he decides not to destroy the chair.

Homer and Bart return to Springfield, unaware they left Homer's electric hammer at the museum. Later when the family watches the news on television, Kent Brockman announces that the chair and electric hammer have been discovered at the Edison Museum and are expected to generate millions for Edison's already wealthy heirs, to the ire of the family.

"The Wizard of Evergreen Terrace" was written by John Swartzwelder, who had a deal with the producers of the show to write five scripts for season ten. Although he was the one who wrote the episode, Dan Greaney was the one who came up with the idea for it. Greaney based Homer's intense obsession with Edison on the fact that when he himself would have an obsession with something in life, he would badger and bore people with details of it. "Homer's relationship to Thomas Edison's achievements is a version of my own experience of trying to communicate the experience of things you love by driving people crazy," Greaney said in a DVD audio commentary for the episode.^[2] The untippable chair was also an idea of Greaney's; while working on the episode, he was leaning back in his chair and fell backwards. He casually said it would be great if there were legs on the back of the chair and someone in the writing room said that would be a great invention for Homer.^[3] Soon after coming up with the story, Greaney told it to Swartzwelder so that he could turn it into a script. Greaney said "it couldn't in my best dreams have turned out as good as it did if I had written it."^[2]

Mark Kirkland was the director of "The Wizard of Evergreen Terrace". He recalls that when he attended the table-read for the episode, the staff thought it was "hilarious" and they could tell it was "going to be a good one." It was the last episode to be produced during the season nine production run and because it takes several months to complete the production of a single episode, it had to air as a hold-over in the upcoming tenth season.^[4] It was decided that "The Wizard of Evergreen Terrace" would be the premiere episode of season ten. As a result, the annual premiere party was held at the Museum of Science and Technology in Los Angeles – it was a tradition for the premiere party to be related to the premiere episode.^[3]

Kirkland cites his assistant director Matthew Nastuk as a big influence on the episode. He became heavily involved with the animation because he had grown up in New Jersey, where the Thomas Edison National Historical Park that Homer and Bart visit is located. To help make the museum look as authentic as possible, Kirkland and Nastuk visited it and took a large number of photographs that they brought back to the animation studio.^[4] At one point in the episode, Homer writes complex math formulas on a chalkboard. The producers wanted them to be actual formulas, so writer David X. Cohen got in contact with a professor at the Massachusetts Institute of Technology who were able to provide them.^[3]

The episode features a guest appearance by actor William Daniels as KITT, a character from the Knight Rider television series of which Homer is a fan.^[3][5] KITT is an artificially intelligent electronic computer module installed in an automobile. In the episode, after failing to cheer Homer up with a film reel of his life, the family shows him a video featuring KITT. The automobile, seen driving in the desert, tells Homer the following: "Hello Homer. It's me, KITT, from TV's Knight Rider. Your family has asked me to invite you to a very special ..."; the film reel breaks just before KITT finishes his sentence. This of course leads to Homer becoming even more depressed.^[5] Daniels' appearance in "The Wizard of Evergreen Terrace" was the first and only time that he voiced KITT outside of Knight Rider and the film Knight Rider 2000. He recalls that "when I told my son in New York that I was going to be on The Simpsons, I think that was the first time that he was really impressed with what I was doing! The Simpsons is a great show and I'm glad they thought of KITT in one of their jokes."^[5]

In its original American broadcast, "The Wizard of Evergreen Terrace" finished 25th in the ratings for the week of September 14–20, 1998, with a Nielsen rating of 8.0, equivalent to approximately 7.95 million viewing households. It tied with Beverly Hills, 90210 and Home Improvement for the 25th place. The episode was the third highest-rated show (tied with Beverly Hills, 90210) on the Fox network that week, following Ally McBeal and Party of Five.^[6]

"The Wizard of Evergreen Terrace" has received generally positive reviews from critics. James Plath of DVD Town thought it had strong writing.^[7] The authors of the book I Can't Believe It's a Bigger and Better Updated Unofficial Simpsons Guide, Warren Martyn and Adrian Wood, called it "a terrific episode, full of wit and sly digs at our expectations of Homer's abilities. The fact that he invents things that other people find useful (and steal the credit for) is both amusing and a little sad. Poor Homer."^[8] Writing for DVD Movie Guide, Colin Jacobson commented that "though 'Wizard' borders on 'Homer’s wacky scheme' territory, his attempts to come up with something significant offer amusement. At no point does 'Wizard' threaten to become a particularly strong episode, but it entertains to a reasonable degree. I do like the 'Everything’s Okay Alarm' and the makeup gun, though."^[9]

Although "Lard of the Dance" aired as a teaser episode a month earlier, "The Wizard of Evergreen Terrace" was the official season premiere of The Simpsons' tenth season. Don Aucoin of The Boston Globe wrote that "It is gratifying to report that, based on the season premiere, The Simpsons promises to remain the most reliable half-hour of laughs on television."^[10] Similarly, David Bianculli of The New York Daily News reported that "The Simpsons is one series that, year after year, remains fresh and funny and lively and surprising. Based on tonight's season premiere, that amazing streak is in no danger of ending."^[11] Lauri Githens of The Buffalo News gave the episode a 5/5 rating, commenting that it shows that "This cynical, bleak yet somehow still hopeful comedy is nowhere near midlife crisis with Season No. 10. It's still fall-down funny. Thank God."^[12] She cited Homer's line to Marge as he and Bart leave for the Edison Museum, "I'm-taking-Bart-over-state-lines-back-soon-I-have-your-wallet-bye!", as the best line of the episode.^[12]

The Lexington Herald-Leader's Heather Svokos was not as pleased. She stated that "As always, the show is better written than most anything on TV, but for a 10th season premiere, it didn't blow me out of the water."^[13] In addition, Phil Kloer of The Atlanta Journal gave the episode a C grade, calling it an "off episode". He commented that it "doesn't have the zing that most Simpsons episodes do." Kloer did, however, enjoy Homer's inventions such as the hamburger earmuffs and the make-up gun, and Homer's line to Marge before he shoots her with it: "Try to keep your nostrils closed."^[14] Marge's response after being shot, "Homer! You’ve got it set on whore!", was commended by The Gazette,^[15] DVD Verdict,^[16] and Ian Jane of DVD Talk, who called the scene the highlight of the episode.^[17]

In his 2015 book The Simpsons and their Mathematical Secrets, British particle physicist Dr. Simon Singh wrote that in the episode, Homer writes an equation on a chalkboard and “If you work it out, you get the mass of a Higgs boson that’s only a bit larger than the nano-mass of a Higgs boson actually is. It’s kind of amazing as Homer makes this prediction 14 years before it was discovered.” He stated that the mathematical backgrounds of many of the show's writers made it the "most mathematical TV show on prime-time television in history", and it could "encourage and nourish" young people with an interest in mathematics.^[18]

• Thomas Edison in popular culture

• Davis Walter; Dreibelbis Gary; Blythe Teresa; Scales Mark; Ashburn Donald; Winans Elizabeth (2001). "The Simpsons". Watching What We Watch. Westminster John Knox Press. pp. 38–63. ISBN 978-0-664-22696-1.
• Halpern, Paul (2007). "Do'hs ex Machina". What's Science Ever Done For Us?: What the Simpsons Can Teach Us About Physics, Robots, Life, and the Universe. John Wiley and Sons. pp. 71–78. ISBN 978-0-470-11460-5.

• "The Wizard of Evergreen Terrace episode capsule". The Simpsons Archive.
• "The Wizard of Evergreen Terrace" at IMDb