In 1952, the Lewton doctrine was put in the mouth of Kirk Douglas as a producer out to do a low-budget number in The Bad and the Beautiful. Douglas, directed in real life by Vincente Minnelli, points out that making the monster visible not only compromises the atmosphere, it cranks up the budget.

This doctrine was a significant factor in Lewton's strain with RKO management. They wanted beasts in the mix, tearing out throats and so on like Universal's wolf man; and they did force him to put shots of a stalking panther into Cat People where Lewton would rather have not. The budget was not an issue in this case as RKO was already renting the panther (Dynamite, by name) and wanted their money's worth. Lewton, and his director - Jacques Tourneur, a Dark Energy hero in his own right - handled these scenes with a good deal of subtlety; but Tourneur, fifteen years later, ran into the same problem with Night of the Demon. This time it was Columbia that intervened, and Tourneur was not there to modify their suggestions. They simply inserted the beastie shots after Tourneur thought he was done.

Actually, the monster as you see him here, stationary, is not a bad bit of work (setting aside Tourneur’s bias for subtlety), but the animation was strictly from hunger, and the demon didn't move all that convincingly... lacked the Harryhausen touch. At any rate, Tourneur made a first-rate film.