 "Cyclical rhythms" represent the short-term fluctuation of economy, while "secular trends" mean deeper long run tendencies, such as general economic growth or decline.The term "contradiction" means a general controversy in the system, usually concerning some short term vs. long term trade-offs.For example, the problem of underconsumption, wherein the drive-down of wages increases the profit for the capitalists on the short-run, but considering the long run, the decreasing of wages may have a crucially harmful effect by reducing the demand for the product.