Steve's barking at desire and ability to pay

 I want to write about what I think is the most obvious and important idea in economics.
With out it there is no economy, that's the desire for something and the ability to pay.
The statement of pay is not necessary money.
Lets assume that a person is in the desert, he needs water to live, and he wants to live. He knows that an oasis is just over the dune. He no longer has the ability to climb the dune, there fore he doesn't have the ability to pay. He therefore dies.
Another travel in the same desert is on the top of the dune and needs the water the same as the first person, but this traveler is able to roll down the dune and reach the water and live. That person had the ability to pay.
Another example. There are two tribes in  the history of early man, both had discovered that they liked to eat meat. One had the knowledge and the ability to hunt, the other didn't. The tribe that couldn't hunt didn't have the ability to pay for the meat but the one who could had a greater ability to eat the meat. The only the first tribe could pay for the if a tribe who could hunt paid it for them or they came a dead animal, having a smaller price to pay which  they could afford.
A different kind of example: A man goes in to a sandwich shop with a half ounce gold coin. He really wants a ham sandwich that sells for 20 dollars, and the gold coin is worth over eight hundred. The proprietor of the sandwich shop has no desire for the gold coin ( he fears that he would lose it and be out of twenty dollars). The man with the gold coin doesn't have the ability to pay, and the proprietor of the sandwich shop doesn't have the desire for the gold coin.
A different kind of example: A person on food stamps has a great desire for a IPad that runs for 500 dollars. The person doesn't normally have the ability to pay for the ipad, but this person discovered that selling part of the food that was gotten with the stamps after several months the ipad is affordable. That person's desire for the IPad is greater then eating all the food. That person then had the ability to pay for the IPad. ( One could reason that this person payed for the IPad with food).
Example:Refuges have no money or any means to pay for their desire to eat. Relief agencies have the ability to pay and they do. (One could argue that this is an ability to transfer the ability to pay).

A company could have the best testing coffee in a land that doesn't drink coffee no one will drink it no matter how easy it is to pay for it.

* The definition that I use for pay is not a common use of the word.