We re-examine firm exploration leading to breakthrough inventions by focusing on a new dimension of knowledge search: the search of originality. We conceptualize firm search types with two distinct dimensions⎯search target and search boundary⎯and propose contrasting effects of the search boundary in which firms search prior original knowledge on the propensities for firms to create path-breaking novelties and high-impact breakthroughs. In particular, we demonstrate that searching original knowledge and incorporating it into research and development makes local search outperform boundary-spanning search in generating high-impact breakthroughs. We argue that this advantage of local search arises from the originality that firms search and revitalize. We find robust support from the analysis of U.S. firm nanotechnology patents between 1980 and 2006. Our findings highlight the importance of searching original knowledge and the benefit of local search in creating breakthrough inventions, thereby suggesting a refinement of the conventional framework of knowledge search.