“The housewife is an unpaid worker in her husband's house in return for the security of being a permanent employee: hers is the reductio ad absurdum of the employee who accepts a lower wage in return for permanence of his employment. But the lowest paid employees can be and are laid off, and so are wives. They have no savings, no skills which they can bargain with elsewhere, and they must bear the stigma of having been sacked.”