In Mankiw's Macroeconomics, he states that, in the short run, an economy's output depends both on its supply and demand for goods and services, because of price stickiness. In the long run, when prices are not sticky but flexible, he states that output depends solely on the supply side, on the availability of capital and labor and the level of technology.
How could demand not matter in the long-run? How could price flexibility in the long run render the will to buy irrelevant to the quantity bought? The absurdity of this question makes me guess that I grossly misunderstood his explanation.
If anyone could shed light on the matter it would be greatly appreciated.