I recently saw an advertisement showing the Wright brothers' aircraft having just lifted off on its maiden flight. The photo in the ad was covered with scribble lines suggesting it was a "vision" conceived in someone's mind that, with additional contemplation, seemed unattainable and therefore should be abandoned in favor of more realistic pursuits.
The ad's obvious implication was not to give up on such future concepts, even when the path to attaining them is not immediately apparent. So many advances in all areas of technology have come about as a result of relentless, and at times discouraging, pursuit of such visions.