Bill I only partially agree with you on this. Personally I believe the reason there are so many frequencies and why so much emphasis is placed on harmonics is because no one is really sure of the EXACTfrequencies that do the job. Harmonics are no different to any other frequency - they are just multiples and generally are weaker than the core frequency.
It is also the reason for the emphasis on power - if you are close but not exact in frequncy then with enough power you are going to do the job anyway. I totally agree with the use of square wave - not because of the harmonics generated but because it is an incredibly destructive waveform.
That's my two cents anyway and i speak from being an electronics technician - previously involved in electronic warfare in the military and via my ability to "see" energy in all things. So I get both sides of the spectrum - scientific and spiritual.
Thanks to all for the wonderful heartfelt intent in these messages.