^ I don't think professional plumbers and accountants exchange services in kind for a living, last time I checked people use this thing called currency.
and this makes the zero sum, since the money plumber pays accountant, is the money he cannot spend on other things like groceries and vise versa.
and this makes the zero sum, since the money plumber pays accountant, is the money he cannot spend on other things like groceries and vise versa.