There is reason for this shift of emphasis from any actual price to a hypothetical 'equilibrium' price. It is usually more interesting to know where a train is going than to know exactly where it is at any moment. The 'equilibrium' position of any price, wage, firm, industry, or system is the position toward which it is tending. The importance of equilibrium analysis, then, is that it enables us to discuss the directions of change. If a train is in New- York and its 'equilibrium' position is in Chicago, we are reasonably confident that the general direction of its motion will be westward, even if it unaccountably decides to travel north for the first hundred and fifty miles.