Steve's discussion is an interesting one related to the understanding (and possible manipulation) of mental states.
I do not sdee my mental states as oscillating waves, but I sure can see them as I can see my arm and my leg. In my case they are often triggered by external simuli but often they pop out apparenlty without reason.
I remember now, in the past I used to suffer stretches of mild mental depression. There was no apprent cause. now it happens no more. Understanding the provenance of such negative states may help us in manipulating them
It cleared up things a bit when I read in the lessons that every mood that we have is a result of previous karma. The more we meditate... the more we are exposed to higher frequencies which transform us. The power of attraction to mental concepts and people is often compelling beyond belief. Until we have actually experienced our passions and desires personified it is difficult to believe we could be controlled by them. Sometimes it takes years later to see beyond those attractions into the illusions created that also are part of their true colors. Once we see the true colors of something or someone we are much more able to let them go. Or on the contrary we may also find that there true colors were a much higher frequency then we were cognizant of. They were a true blessing we were not able to fully understand.