it was there in every negotiation and would be for as long as necessity drove the trading system - the need for particular things ( such as spice or the technoproducts of ix ) , the need for specialists ( such as mentats or suk doctors ) , and all of the other mundane needs for which there were markets : for labor forces , for builders , for designers , for planiformed life , for artists , for exotic pleasures ... no legal system could bind such complexity into a whole and this fact quite obviously brought up another necessity - the constant need for arbiters with clout .