In physics, the behaviour of elementary particles gave rise to quantum mechanics while Newtonian theory sufficed for the behaviour of objects containing many particles. In the canonical theory, all agents can distinguish between every state of nature and know their probabilities of occurrence, while in the sequence economy they additionally know spot prices conditional on event and date. These are extremely limiting assumptions. In A–D equilibrium analysis excess demands are maps from the space of A–D prices. This space considers goods at different dates and locations and in different states of nature and of different specification as different. Notice that no expected prices are involved. At the very least this means that there is a way in which agents at one moment of time can deal in all these goods – A–D prices are market prices or ''virtual'' market prices.