The author, Robert C. O'Brien, was inspired to write Mrs. Frisby and the Rats of NIMH after seeing the work of John B. Calhoun. Calhoun had an idea: that human society breaks down when we get too crowded. To test his theory, he introduced eight mice into something called the "Mouse Universe," an enclosed space with no predators, plenty of food and water, no disease, no bad weather and no hope for escape. The mice doubled in numbers every 55 days until there were about 600 of them.
And this was when things got weird.
Yoichi R. Okamoto