Hello
I think that inflation is not so natural. To cause inflation should be more difficult over time, while deflation should be natural and should be caused when no new inventions reach the market.
I explain myself, with gold:
Inflation
When gold started to be valuable, there be lots of it on the surface, on the rivers on many places. Now, one needs to mine 1 ton of dirt to have one ounce of gold, and it will be more difficult over time. That is natural, because once a valuable commodity is extracted, it is more scarce in the source and more difficult to get from it.
Deflation
When the market is empty from products, the market needs all of them, and only small number of sources are available, then, the prices go up. But after a while, more and more people have the product and the market begins to saturate. Eventually everyone who is interested in that product have it, so the people starts saving. That causes deflation, because prices needs to drop to attract people that has been not interested on the product at current price.
But then, someone invents something new, and because it is new, it can create a new market, and attract new people that wants it. That reduces deflation to the point that prices start increasing for a while. The equilibrium of new inventions and saturated market is what should mainly control the prices and the availability of money (something valuable and scarce), and the more and more scarce source of the resource should intervene less and less over time in the inflation/deflation cycle.