An economy grows, reaches a peak, then begins a downturn, followed by a period of negative growth (a contraction), that ends in a trough before the next upturn. these ups and downs in an economy are often referred to as

necessary and proper clause. the congress shall have power to all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states, or in any department or officer thereof.

cultural/diplomatic relations. most medieval japanese   culture has chinese origins. writing, architecture etc.