If controlling the volume of money is what controls the value of money, then what we mean by the value of money is only relative to the principles - or lack thereof - that man enacts towards that volume control.
Money - the paper and metal circles - in and of itself is valueless, and is supposed to be. The only thing that makes them different from any other piece of paper or any other piece of metal is that they are made/printed/minted by the passing of the law - or, in the case of today, the passing of the law being forfeited to private banks. Either way, money happens through the passing of the law.
There is no other way that money happens: it always happens from some form of central governance. If that central governance (the privilege of printing money being the inherent right of a government) is forfeited to private institutions and this forfeiting called "private regulation" or "leaving it to the free market" or whatever terms you want to use, then you have not decentralized a damn thing. You have just made central power beyond the reach of the public domain and have enslaved the public. Goodbye common good. Hello plutocracy.
Realize where central governance has its proper place.
The paper and metal circles do not gain an inherent value at any point in time, though at points in time they are traded as commodities in the market place (and a money's tradeability only means the economy that the money serves is doing well - or, in the case of today, doing better than another); but they can be traded for all manner of things in the market place. That is what the passing of the law did when it made the money. One can use money to buy gold, or one can use money to buy licorice root. The seller receives the money knowing he can in turn use it to buy all manner of things in the market place.
When this principle of money is not corrupted, it not only works, but it works very well. England flourished using mere sticks of wood.
When we say that a money has become devalued due to, for instance, a counterfeiting inflation of the volume, it is not the superfluity itself that has devalued the money, as though its opposite scarcity would then imbue it with value. It is the disproportion of the volume of the money to the productivity, population, labours, gross domestic product, and so forth, of man.
Thus when the volume is inflated disproportionately, that means that the activities of man must make an unnatural strenuous effort to keep the money's commensurate purpose going, rather than the money easing the activities of man; again, not because the money itself has become valueless as though it had inherent value before, but because the money's commensurate purpose has then become redundant.
Likewise, the same for contraction, or disproportionate deflation. That is when the money's commensurate purpose is, of course, inoperative, because the volume of the money is rendered scarce rather than plentiful. And then people suffer in the midst of plenty, as they did during the depression of the thirties, during which time the money volume was contracted more and more, year by year, and then further, by being put on the gold standard.
So this is what is meant by saying the money is valuable or is devalued.
In other words, the better that money serves man, the more value it has. When money becomes devalued, it means that the money is no longer serving man, but that man must serve the money.