Let us see now how he deals with the other objection. If labour is just value-forming substance, and if value is just preserved labour, then nothing which has cost labour should be destitute of value. But Marx frankly admits that there are such things which have yet got no value; and they have no value, he explains, because they have no utility. "Nothing can have value without being useful. If it is useless, the work contained in it is useless, and therefore has no value." He goes further; he says that a thing may be both useful and the product of labour and yet have no value. "He who by the produce of his labour satisfies wants of his own produces utility but not value. To produce a ware, _i.e._, a thing which has not merely value in use, but value in exchange, he must produce something which is not only useful to himself, but useful to others," _i.e._, socially useful. A product of labour which is useless to the producer and everybody else has no value of any sort; a product of labour which, while useful to the producer, is useless to any one else, has no exchange value. It satisfies no want of others. This would seem to cover the case of over-production, when commodities lose their value for a time because nobody wants them. Lassalle explained this depreciation of value by saying that the time of labour socially necessary to produce the articles in question had diminished. Marx explains it by saying that the labour is less socially useful or not socially useful at all. And why is the labour not socially useful? Simply because the product is not so. The social utility or inutility of the labour is a mere inference from the social utility or inutility of the product, and it is therefore the latter consideration that influences value. Marx tries in vain to exclude the influence of that consideration, or to explain it as a mere subsidiary qualification of labour. Labour and social utility both enter equally into the constitution of value, and Marx's radical error lies in defining value in terms of labour only, ignoring utility.