I think Jeff Greene claims too much in his Pluto books where he equates Pluto with the soul. The soul has to be more than the entire chart. I think the chart says a lot about the soul's incarnation.
Yes I know what you mean. I think it was Howard Sasportas who said that Mars is the energy to do work in the world; Pluto is the energy to do work in the underworld. Maybe Pluto symbolises the expression of the will of the soul, just as Mars symbolises the expression of the will of the individual. Lower-higher octave stuff, I guess - Mercury is the mind of the individual so maybe Uranus is on one level the mind of the soul, Venus is the for relationship in the individual and so perhaps Neptune is the Soul's urge to merge with other souls.
Sasportas also described Mars as the henchman of the Sun, which perhaps makes Pluto the henchman of the soul!
This is a quote from a book I dipped into yesterday - Healing Pluto Problems, by Donna Cunningham:
'When we do not give ourselves time to regenerate and to process new stages of life, resentment and grief can build up to toxic levels....Time alone [ie time spent alone] can give us guidance from our Higher Selves...In the old days we had retreats and monasteries. Today the average person has nothing like that and little awareness of the need for it. Today we have cancer.'
I guess when we're struggling against Plutonian processes, we are like a child having a tantrum - completely unable to hear the voice of reason from the parent who has our best interests at heart. We're metaphorically screaming too loud to hear the guidance.