It's neither Big Data nor innovation, despite all the business books and management gurus touting the disruptive potential of each.
It's the simple question, right there on the tip of your tongue.
A new book demonstrates just how far an inquisitive mind can take you.
Change usually starts with a question. Inquiry has toppled monarchs and empires throughout history.
It's the basis of one of the earliest forms of education - the Socratic Method - used to train young minds in the rigours of critical thinking.
Yet, it's a mostly ignored business tool, overlooked by executives trained in the MBA arts that "tend to place more value on answers, pronouncements, and promises," according to author Warren Berger.
Questions also overturn business empires.
Nagging, unanswered thoughts that start with words such as "why" or "what if" often ignite processes that will eventually disrupt well-worn business models, re-jig the balance of power within an industry, and create new markets for products no one had thought of making.
If you could map the DNA of successful entrepreneurs, it might reveal a double helix of question marks, he says.
Mr Berger, a journalist and innovation expert who has written for 'Wired' and 'BusinessWeek', points out that, as children, we start out questioning everything. (What parent hasn't been exasperated by the constant "why" from their kids?)
Mr Berger's last book was called 'Glimmer'. It delved into the process behind creative thinking. It was named by 'BusinessWeek' as one of its best innovation and design books of the year.
Mr Berger points out that somewhere in our maturation we lose the innate skill of questioning that we possess as children and become more conformist and - to the detriment of business and society - less creative.
'A More Beautiful Question' reminds us that questions drive so many successful innovations and start-up companies.
The mobile phone, the internet, digital music players, on-line streaming of movies, and so on - all these technological and business model breakthroughs, from Polaroid to Apple, Netflix, and Airbnb, began when someone asked simple questions: "why, what if, or how?"
Mr Berger has previously pointed out that the successful entrepreneur is the one who "steps back" to question what others ignore or take for granted.
The author explains that the art of inquiry also helps employees work collaboratively at companies such as Google and IDEO, which both employ the "How Might We" method of group questioning to build better products and more cohesive cultures.