It has been said that everyone lives by selling something ,in the light of this statment,teachers lives by selling knowledge,philosophers by selling wisdom.priests by selling sprital comfort ,though it maby possible to measure the the value of services which people perform for us ,there are times when we would willing to give everything we possess to save our lives ,yet we might grudge paying the surgeon a high fee for offering us precisely this service ,the condition of society ae such that skills have to be paid for in the same way that goods are paid for at shop ,everyone has something to sell!