What is the meaning of the vacuum story that Nicodemus tells Mrs. Frisby in the book Mrs. Frisby and the Rats of NIMH?

The aim of the vacuum story was to inform Mrs. Frisby about the risks of taking the easy way out. This was with regards to the stealing culture of the rats. Nicodemus realized that by over-relying on the resources available to the people, the rats were exposing themselves to conflicts with the humans. He believed that taking the provisions from the people was going to be unsustainable in the long run because the resources were limited and a significant reduction would force the people to capture or exterminate them. In this regard, Nicodemus sought to establish a self sufficient community for the rats to safely exist in, far from the threat posed by the humans.

In the vacuum cleaner story, Mrs. Jones substituted her traditional use of the broom and the mop for the more effective vacuum cleaner. The other women followed suit much to the detriment of their environment. The power company, in their attempt to supply the much needed electricity, polluted the environment because of the soot produced by the plant. This forced the women to work twice as hard and long and they still did not achieve the same levels of cleanliness that they did when they used the broom and mop.

The meaning of the story to the rats was over-reliance on shared resources (stealing) was risky but easy, while on the other hand, self sufficiency needed more effort but offered safety in return.