How sweet it is to find a movie in which the hero, having lusted after purely carnal pleasures for much of its length, finally falls in love with a woman's mind. That there is nobody attached to it, that it is, in fact, a brain Kept alive in a bottle by a half-mad scientist, might strike some people as a little funny. It will strike vaster numbers of them as very funny—especially after Steve Martin pastes plastic lips on the bottle so he can kiss his beloved….

[The Man with Two Brains] is the most assured and hilarious of the three Martin-Carl Reiner collaborations. There is something classically American about its monomaniacal pursuit of a gag every five seconds, characterization and redeeming social value be damned. The movie is rather like a Henny Youngman monologue combined with a National Lampoon spread. And it offers reassuring proof that...