They coached their apprentices in all of the principles they had learned along the way—the benefit in looking for new applications of existing technology and needs that are not being met; the importance of maintaining the closest possible relationship with customers; the need to keep ideas as simple and realistic as possible; the value of creating a superior product and of winning through craftsmanship, as opposed to fixating on making money.
As their apprentices learned, they learned as well. Oddly enough, they discovered that what really makes successful entrepreneurs is not the nature of their idea, or the university they went to, but their actual character—their willingness to adapt their idea and take advantage of possibilities they had not first imagined. This is precisely the trait—fluidity of mind—that Graham had identified in himself and in other inventors.
The other essential character trait was supreme tenacity.
Mastery by Robert Greene