over general equilibrium on the grounds that the inherently dynamical nature of economics made the former more practically useful. Much of the success of Marshall's teaching and Principles book derived from his effective use of diagrams, which were soon emulated by other teachers worldwide. Alfred Marshall was the first to develop the standard supply and demand graph demonstrating a number of fundamentals regarding supply and demand including the supply and demand curves, market equilibrium, the relationship between quantity and price in regards to supply and demand, the law of marginal utility, the law of diminishing returns, and the ideas of consumer and producer surpluses. This model is now used by economists in various forms using different variables to demonstrate several other economic principles. Marshall's model allowed a visual representation of complex economic fundamentals where before all the ideas and theories were only capable of being explained through words. These models are now critical throughout the study of economics because they allow a clear and concise representation of the fundamentals or theories being explained. Theoretical contributions Marshall is considered to be one of the most influential economists of his time, largely shaping mainstream economic thought for the next fifty years, and being one of the founders of the school of neoclassical economics. Although his economics was advertised as extensions and refinements of the work of Adam Smith, Thomas Robert Malthus and John Stuart Mill, he extended economics away from its classical focus on the market economy and instead popularised it as a study of human behaviour. He downplayed the contributions of certain other economists to his work, such as Léon Walras, Vilfredo Pareto and Jules Dupuit, and only grudgingly acknowledged the influence of Stanley Jevons himself. Marshall was one of those who used utility analysis, but not as a theory of value. He used it as a part of the theory to explain demand curves and the principle of substitution. Marshall's scissors analysis — which combined demand and supply, that is, utility and cost of production, as if in the two blades of a pair of scissors — effectively removed the theory of value from the center of analysis and replaced it with the theory of price. While the term "value" continued to be used, for most people it was a synonym for "price". Prices no longer were thought to gravitate toward some ultimate and absolute basis of price; prices were