Say's Law of Markets is a principle attributed to the French classical economist Jean-Baptiste Say. The law states that "supply creates its own demand." The core idea is that the very act of producing goods (supply) generates an equivalent amount of income (in the form of wages, rent, interest, and profit) for the factors of production. This income is then used to purchase the goods and services that were produced. The law implies that there cannot be a general overproduction or glut in the market in the long run.