With the opening of Mike Nichols' and Eric Idle's "Spamalot" on Broadway last month, it's a good time to revisit the 1975 comedy classic that inspired the musical. Thirty years have elapsed since its original release, but it is still a movie that veers wildly back and forth between hilariously inventive and downright silly.  If you can hold on tight, it's a worthwhile ride. Almost arbitrarily about a band of adventurers looking for the famed Holy Grail, the movie is just an excuse to create a nonsensical world steeped in medieval history and comically ironic violence. Directed by Terry Gilliam and Terry Jones, it is typical Monty Python fare, which means a lot of clever wordplay and elaborate sight gags with big payoffs. The story begins with King Arthur and his page Patsy galloping on their invisible horses with their clapping coconut half-shells, as they search for worthy knights to take back to Camelot. From there, we meet a cast of characters that only makes sense in Python-land: an increasingly armless and legless Black Knight with a chip on his shoulder, a big Trojan Horse-like wooden rabbit, some disrespectful Frenchmen, castle-bound nymphomaniac maidens, the knights who dare to say "Ni!", a pedantic historian in the present day and even God, who seems rather impatient with the befuddled knights as He explains their quest for the Holy Grail. Amid these disparate elements, the film holds together as a clever satire on blind pious ignorance and the unquestioning acceptance of organized religion. The pacing gets sluggish toward the end, but the conclusion is riotous and just in time.