Demand curve confusion My economics textbook says that demand curves slope downward - but then goes on to say that when demand increases, prices go up! Does anyone else find this confusing?

Edit: from the small number of answers I have received, it seems that this is not a well understood issue in economics. Is anyone aware of alternative approaches which avoid this contradiction (e.g. I have heard that the Austrian School does not use demand curves)?
The book probably intends you to think like this



so you have a downward-sloping demand curve (lower prices lead to higher demand), but if demand increases for a reason not related to price (a shift from the Demand 1 curve to the Demand 2 curve) then the new equilibrium on the upward-sloping supply curve will be at a higher price and quantity

There are a lot of implicit assumptions here, especially 


the direction of the slope of the supply curve
whatever changed the demand curve did not affect the supply curve