The plastic educator has a side effect that serves as the mystery at the dark heart of the film. Use of the device gives rise to “monsters from the id,” which manifest while the user is asleep and attack the sleeper’s enemies. Our first clue to the origins of the monster appear when Morbius explains the Krell gauges.
The encyclopedia registers a negligible amount of power.
“Gauges line the curving walls of the lab in stacks of two,” Morbius explains, “Their calibrations appear to indicate that they are set in decimal series, each division recording exactly ten times as many amperes as the one preceding it. Ten times ten, times ten, times ten, times ten, times ten, on and on and on, row after row, gauge after gauge.”
He turns on the encyclopedia and a small bit of light appears on the first gauge. He turns on the plastic educator and the gauge shows a little more.
Asleep, Morbius’ id manifests as a horrible monster.
This explanation helps to set up the awesome power of Morbius’ monster when we see Morbius sleeping in the lab, and sixteen of the gauges are lit up. (It’s 10^16 times more powerful than an encyclopedia.) We know the (then) unbelievable technologies showed the barest sliver of a reading, and here they are blasting power to…somewhere.
After waking, both Morbius’ monster and the power gauges fade.
The connection is severed as Morbius awakens, and within seconds the monster fades and the gauges behind him dim one by one.
Adams wrestles Morbius into the seat of the educator.
This dramatic link is underscored when the monster has come into the underground city to destroy Morbius, Adams, and Alta. As Adams wrestles Morbius down, we hear the angry pounding of the monster against the vault like doors, and see the gauges glowing and fluctuating wildly in the background.