Only when crop yields increased, steam power was developed, and textile fabrication became more efficient were available work hours freed for the production and consumption of more discretionary goods and services.

• 只有当作物产量提高，蒸汽动力得以开发，纺织效率提高时，现有的工作时间才能腾出来，生产和消费选择性较大的商品和服务。