Selling means getting the right man, at the right time, to make the right decision of his own choosing.
US economist Peter Drucker once said that there was one key aspect common to all successful people. And that was their ability to narrow the gap between decision and execution. In sales, too, it is not only motivation but also volition that is responsible for the successful deal.
Assuming you are in the right place at the right time with the right product - that is ONE art.
Assuming you are also equipped with empathy and selling competence, both of which can be learned, and your product or service is literally ripped from your hands - that is THE art.