A foolish constancy is the hobgoblin of little minds and of some movie critics (who may or may not have little minds) when writing about the films of comedians. In his own day, poor old W. C. Fields was always being rapped for not making movies that were as funny, from start to finish, as his adoring critics found bits of them to be. I'm afraid that once or twice I've gone so far as to suggest that a certain film by Mel Brooks hasn't been consistently funny, that is, that there were some parts that weren't as funny as other parts. However, as any surveyor of anything will tell you, you can't have a high spot unless you have a low one from which to survey it. All of which is a roundabout way of saying that "Monty Python and the Holy Grail" has some low spots but that anyone at all fond of the members of this brilliant British comedy group…shouldn't care less. "Monty Python and the Holy Grail," which opened yesterday at the Cinema 2, is a marvelously particular kind of lunatic endeavor. It's been collectively written by the Python troupe and jointly directed by two of them (Terry Gilliam and Terry Jones) so effectively that I'm beginning to suspect that there really aren't six of them but only one, a fellow with several dozen faces who knows a great deal about trick photography. Unlike "And Now for Something Completely Different," which was a collection of sketches from "Monty Python's Flying Circus," television show, "Monty Python and the Holy Grail" is what is known on Broadway as a "book show." It has a story with an approximate beginning, an approximate middle and it ends, or perhaps I should say that it stops after a while. To be more specific, it's the Python troupe's version of the legend of King Arthur and the search for the holy grail, with no apologies at all to Malory though it manages to send up the legend, courtly love, fidelity, bravery, costume movies, movie violence and ornithology. Graham Chapman plays Arthur, the film's major continuing character, with the earnest optimism of a 19th-century missionary, who's doomed to fail but refuses to acknowledge the fact. The other members of the Python team turn up in a variety of roles—Round Table knights, snobbish French aristocrats, irritable serfs, mythical monsters and, in one case, as a noble son named Alice who tries to turn the film into an operetta. The gags are nonstop, occasionally inspired and should not be divulged, though it's not giving away too much to say that I particularly liked a sequence in which the knights, to gain access to an enemy castle, come up with the idea of building a Trojan rabbit. When Arthur calls retreat, he simply yells: "Run away!" And the morale of Sir Robin, the least successful of the Round Table knights, isn't helped by a retinue of minstrels who insist on singing about his most embarrassing defeats. I have no idea whether Mr. Gilliam and Mr. Jones have seen Robert Bresson's rather more austere film, "Lancelot of the Lake," but there are times when "Monty Python and the Holy Grail" seems to be putting on Mr. Bresson unmercifully. The dour lighting and landscapes that are so important in the Bresson film are tossed into this comedy without apparent thought for the havoc they do "Lancelot." Mr. Bresson's emphasis on what you might call the sound of knighthood (clanking armor, horses' hoofs) is also hilariously parodied, as well as the violence of the age, on which the Python people have the last bleeding word. Everyone interested in Mr. Bresson would do well to stay away from "Monty Python and the Holy Grail" until after they see "Lancelot." The comparison, which may never have been intended, is nevertheless lethal to the work of the great French director. — New York Times