Reserve Currency and Wittgenstein What is the value of your service if only you can perform it and I need it? Well, it depends how badly I need it. What is the value if everyone in the world can do it? Surely much less. Supply and demand they say.
As it relates to currency. It is little more than a promissory note. The value is created by the perception of the individual who receives it, backed up and assured by the legitimacy and might of the issuer.
Why is it important? Why don't we just barter? One of the most obvious practical reasons being sometimes items of value are substantial in size. You wouldn't want to enter a market lugging a marble sculpture just to purchase a diamond ring would you? From this realization comes the idea of deeds or contracts ie. written and signed papers that mandate what is who's and for what or why. These documents can be forged, lost, stolen, and much more. It also prevents compartmentalization of value for security. Example, you can put a few thousand in the market, a few thousand in land, a few thousand in material goods, a few thousand buried here, buried there, etc.
There are plenty of downsides but most that can be redeemed. One if not the most important thing about currency in general is that it makes savagery and brutality unnecessary to get and keep what one wants. You need a home, food, stuff, you just rob someone and they will more than likely give you the pieces of paper you need for all that. You no longer have to bash someone over the head for shelter or something to eat or wear. Not to say this stops some cash thieves. It's just after you get what you want you can spend it anywhere as opposed to having to kill a person to stop them from taking the shelter or item back. Again, assuming you get away with the cash robbery. It's just paper. Very different from someone wondering why you suddenly have 50 prime cattle in your yard after hearing about a dozen monks were found slaughtered nearby with their cattle stolen.