Money always begins as a real commodity with independent value, but can remain valuable later after the commodity loses all independent value. Gold and silver most common versions. National governments gradually monopolized supply of paper money, but at first kept the tie to gold. Money Supply and Money Demand People use money to buy goods. But we can flip perspectives and say that people are using goods to buy money.
P is, the MORE they want.
People often assume that the quantity of money people want is exactly proportional to the price level. People actually want a given amount of REAL purchasing power. But it is better to say that interest rate changes shift the money demand schedule. If interest rates increase, people lose more interest by holding money instead of interest-bearing assets. Interest rate decreases make money demand increase.