The Mercantilist School never presented a common front but is associated with a common outlook: the idea of specie or bullion as the essence of wealth and the notion that a positive balance of trade is an index of national welfare. It is also associated with an emphasis on population growth and low wages, a concern with full employment and the far reaching denial of foreign trade as a source of net gain to the world as a whole; that is, international trade was regarded as a zero-sum gain and particular nations were thought to benefit from international trade only at the expense of others. The underlying idea that a permanent balance of trade surplus should be beneficial to a nation has been a source of discussion right down to the present day.