Visuality aside, I believe that if you are taking the course of information we all see daily as (metaphorically) a flow of water, then editing is narrowing down a river to a garden hose (again metaphorically). If you are reducing the scary amount of information to a smaller state, reducing the disorder, then (to me) that is an act of editing. Yes, editors select and organize. That is part of their gig. The editor of an academic book filled with her colleague's work is arranging and organizing, but the reason she was invited to build that book is because she can see the wider seascape and can see the importance of the essays that she selected. That winnowing down to a smaller selection, presenting the original essays without lengthy comment, is an act of editing. Writing a new book that quotes those same essays with new original comments for each and charts how these same essays relate to a wider story, is what curating is to me.
It's publicly adding original information to an existing body of work.
So on to Perl
The challenges involved in such curatorial work are the challenges of interpretation. Scholarship and erudition are essential. So is an instinctive feeling for the freestanding value of the work of art. And all of this must be combined with a sense of how works that emerged in a particular time and place can most effectively be presented in another time and place—in a way that is true both to the past and to the present.
Perl's notion is that real curators are there to present the contextualization of objects, ideas, and situations, and this rings true to me. Curating is the activity of knowing a subject and being able to add to it rather than arrange it.
A consequence of this notion is that it would be easy to say I think that editing isn't scholarly but curating is. I think that editing is equally academic, but it doesn't function synthetically. Editing is analytic and curating is synthetic. For an edited book of essays synthesis happens in the readers mind rather than in the creation of the book.
the unexpected links between fifteenth-century Italy, Oscar Wilde’s England, and New York today
That's what a well curated show delivers. Unexpected relevance.