Gertrude McFuzz. The Wickersham Brothers. Sour Kangaroo and her son. Horton the Elephant. The Who’s down in Whoville. We grew up with them, and now they sing and dance; this weekend only, you can see them all in perfect Seussian style.

“”Seussical the Musical,”” a full-length musical theater production based on the stories and characters of the internationally loved children’s book author Dr. Seuss, opened Oct. 29 to a packed house at the Civic Theater downtown. Written by the Tony Award-winning writer Lynn Ahrens (lyricist and playwright) and Stephen Flaherty (composer and playwright) of “”Ragtime”” and “”Once on this Island”” (last year’s Muirsical production), “”Seussical”” taps into that beautiful place in the adult psyche where it’s still fun to be a kid.

The cast of “”Seussical”” is headed by Dr. Seuss’s most beloved character, The Cat in the Hat, played by “”America’s Sweetheart of Gymnastics”” and the quintessential Peter Pan, Cathy Rigby. The Cat in the Hat serves as a guide to young Jojo (Richard Miron) and shows him the wonderful extremes that his “”thinks”” can take him if he sets his mind to it. Along the way, Jojo befriends Horton the Elephant (Eric Leviton), with whom he bonds and helps put his life into perspective. With costumes and sets whose style lies somewhere between “”The Lion King”” and a filled-out coloring book, “”Seussical”” is quite the optical sight.

One of the darling aspects of “”Seussical”” is Rigby’s penetration of proscenium and physical involvement with the audience. At one point, Rigby grabbed a boy out of the crowd (with his mother standing by) and had him conduct the pit orchestra. At another dramatic point in the show, Rigby stopped the show and covered the first row of patrons with Silly String. “”I have to do it, I’m sorry,”” she said, while showering the high-dollar clientele to the booming amusement of the audience and her own personal glee.

With all of the fantastic costumes, sets, characters and situations that appear in a Broadway show, it is amazing that the single most astounding aspect of the performance shone through after the show was over.

After her curtain call, Rigby made an announcement to the audience, which major stars often do on opening nights. On this night, Rigby did not simply thank everyone for coming and giving their time and money to support live theater, but confronted her audience with all due pathos by calling up Audrey Geisel, the wife of the late Dr. Seuss. The woman of far more years than her energy and vivacity would indicate took center stage along Rigby and received a standing ovation. After a short anecdote by Rigby about their first meeting, Audrey Geisel was given the microphone. With the voice of a thousand grandmothers, she shared this simple analysis of the show and the culminating point of her late husband’s work: “”What was lacking in New York …”” — and the entire crowd held its breath — “”… was found here.””

Here, in San Diego. Here, in the heart of the little boy pulled on stage after intermission and given a baton with which he was instructed to conduct the pit orchestra of the Broadway show.

The moment, like the show, was truly magical.

Individual tickets for “”Seussical the Musical”” can be purchased at (610) 570-1100 or http://www.ticketmaster.com.

Seussical the Musical

Thursday through Saturday at 7:30 p.m., Sunday at 1 p.m. and 6 .m.

playing at the Civic Theatre