While studying about the Resonance and Forced Oscillations, I came across a graph in my textbook that is given below:-[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/NFd24.png



Now, the author writes 

> As the amount of damping increases, the peak shifts to lower frequencies.

Why does this happen? And does this imply that at higher damping levels one cannot achieve a higher amplitude by setting the period of the forced oscillation to be equal to the natural frequency? This seems strange because, the highest amplitude is achieved when the natural frequency is equal to the driving frequency. But, I guess that the rules are somehow different for the damping case.