Work that makes an impact in the field, any field, is very difficult to accomplish. Even to make even "a significant contribution," as the cliché goes, can be quite difficult. Let's break this down a little bit.

"Work that makes an impact" is work that is widely quoted, responded to. The closest I've come is with my article "The Avant-Garde and Its Discontents." The Lorca book may have some impact. We'll have to wait and see.

"A significant contribution to the field" is work that is cited once in a while, that you would recommend to graduate students studying up on this particular sub-field.

The best way of having an impact is to do something that seems *obvious* in retrospect. In other words, something that the reader should have thought of doing himself. A major new statement about a canonical author can accomplish this. If it is good, the first book about an author who should be canonical but is not yet (Perloff's Frank O'Hara) will make an impact. A book that puts various things together and redefines a field, like Doris Sommer's Foundational Fictions, which approached the 19th century Latin American novel through the lens of nationalism, is influential in this way, creating a paradigm that others have repeated. You don't get as much credit for writing a book that interprets a few more Lat Am novels using this same paradigm.

I've written things I thought should have made an impact, but didn't. Quality is not enough: sadly, other people have to actually care about what you are writing about. If no one else is writing on the problems with which you are occupied, there will be nobody to cite your work, to argue with your conclusions.

Having an impact will mean: (1) Others will have to cite you, even if they disagree. (2) The critical language others use will be one defined, in part, by you. (3) Your work will be a model or paradigm, or offer models and paradigms.