self-sufficiency. Instead of the specialisation of economies advocated by the Ricardian theory of comparative advantage, he prefers the maintenance of a diversity of activities for nations. In it he refutes the principle of peacemaking trade. His vision of trade became that of a system where foreign capitalists compete for new markets. He defends the idea of producing on national soil when possible and reasonable and expresses sympathy for the advocates of protectionism. He notes in National Self-Sufficiency: He also writes in National Self-Sufficiency: Later, Keynes had a written correspondence with James Meade centred on the issue of import restrictions. Keynes and Meade discussed the best choice between quota and tariff. In March 1944 Keynes began a discussion with Marcus Fleming after the latter had written an article entitled Quotas versus depreciation. On this occasion, we see that he has definitely taken a protectionist stance after the Great Depression. He considered that quotas could be more effective than currency depreciation in dealing with external imbalances. Thus, for Keynes, currency depreciation was no longer sufficient and protectionist measures became necessary to avoid trade deficits. To avoid the return of crises due to a self-regulating economic system, it seemed essential to him to regulate trade and stop free trade (deregulation of foreign trade). He points out that countries that import more than they export weaken their economies. When the trade deficit increases, unemployment rises and GDP slows down. And surplus countries exert a "negative externality" on their trading partners. They get richer at the expense of others and destroy the output of their trading partners. John Maynard Keynes believed that the products of surplus countries should be taxed to avoid trade imbalances. Views on trade imbalances Keynes was the principal author of a proposalthe so-called Keynes Planfor an International Clearing Union. The two governing principles of the plan were that the problem of settling outstanding balances should be solved by "creating" additional "international money", and that debtor and creditor should be treated almost alike as disturbers of equilibrium. In the event, though, the plans were rejected, in part because "American opinion was naturally reluctant to accept the principle of equality of treatment so novel in debtor-creditor relationships". The new system is not founded on free-trade (liberalisation of foreign trade) but rather on the regulation of international trade, to eliminate trade imbalances: the nations with a surplus would have an incentive to reduce it,