Napoleon didn't clarify, I don't believe. The quote was "I would rather have a general who was lucky than one who was good." Certainly, "Beyond possible comprehension by others" isn't what I mean or a likely interpretation. "Succeeded for reasons beneath others notice" would be more the idea. As an example, Grant's tendency to thoroughly disambiguate his orders and always put them in writing (after a Shiloh order debacle) helped his luck a great deal. But it isn't something others would necessarily notice or be in a position to notice. Sheridan had some astonishing luck, but it was possible because he insisted his subordinates (each taking separate routes) be highly disciplined and courageous and get to each point exactly on time, no matter what. (Later, one of those subordinates, Custer, would be cut down because his peers didn't fulfill their orders and arrive on time to join him in battle despite all - and because he did push on as he'd been taught. Coordination only works if everybody's doing it.)