Relationship between polarization charge density and free charge density

I have concluded that in a uniform dielectric, volume free charge density $$\rho_0$$ and volume polarization charge density $$\rho'$$ satisfy $$\rho' = \frac{-(\epsilon - \epsilon_0)}{\epsilon}\rho_0$$ which can be derived from the differential form of Gauss's law.

It seems to show an interesting fact that $$\rho'$$ is always less than $$\rho_0$$. How do you explain this? Thanks!