Ruins of Old
The Nezumi philosophy is easily summarized: survival of the fittest. Their rough surroundings, short life cycles and fast metabolism makes survival a full time job. With no down time in which to reflect, they rarely look further than the next meal, the next conflict or the next mating opportunity.
A Nezumi that spends time thinking about the universe, the nature of life or metaphysics is wasting precious time that could have been spent striking at enemies to prevent them from striking at it first.