In other words, you must be capable of explaining how the idea will be reproducibly applied in a real world example. But if the inventor actually knows how to build such a machine, he has a great invention. An idea needs to be more than just abstract to be an invention. An inventor does not need to build a model of an invention to make sure that it actually works, only describe how the idea will be embodied or practiced. Most commonly, an inventor writes down an idea and draws pictures or flow charts of how the idea will look or be practiced.
Ideas are powerful because they lead to inventions.
Inventions make daily tasks and products faster, simpler, more attractive, and more profitable.