[Mind's Eye] Greed

Hey everyone... i have been very dull of late with little mind
activity... but.. today i was just going through Hind Swaraj.... and
well its not about the book.. in the review pages.. i read something
about Greed.. and it got me thinking.... only humans have greed
right... i find it very peculiar.. the most common vice one is taught
against from childhood...What is the nature of it... is there or can
there be a why?... when does wanting enough turn to greed.... the
dictionary defines it as wanting more than is necessary.... well..
that appplies to everything then!.. we always have and want more than
necessary or required... is being careful and cautious greedy(in
wanting enough and more)... is being ambitious greedy.... why is being
greedy wrong? ....very simplistic questions.. but i want to know what
everyone thinks about this....