We treat with the knife

I am responding to a researcher's questionnaire about editing and the role of the editor. One question invites me to suggest a metaphor for editing, and the first that occurred to me is one I have made previously in these dispatches: surgery.
Editors must deal with the text as it is. Sometimes the best we can achieve is to make the substandard mediocre, because, as I often quote Anthony Trollope, "One cannot pour out of a jug more than is in it."
So we as editors start looking for diseased tissue to excise. A substantial amount of the work I have done over the past three decades is cutting.* I go searching for cliches, for pleonasms and wordiness, for needless repetitions, for superfluous information, for self-indulgent ornamentation, for mixed metaphors, for factual inaccuracies; at each instance the vorpal blade goes snicker-snack.
When the organization is defective and elements are not in effective order, I do reconstructive work.
In the remote past, when newspapers hired copy editors and I presided over The Sun's brutal applicant test, many applicants would try to show me how much editing they could do on the specimens, finding something to correct in every sentence. Often more than one thing. Perhaps they were puzzled when they were not offered a position, but I couldn't trust them.
The reason is another comparison with surgery: Every time an editor goes into a text, just as when a surgeon opens up a human body, there is a hazard of doing damage, of injuring something that was healthy before. As there is iatrogenic** medicine, there is iatrogenic editing. Editing should be as minimally invasive as necessary, because an error introduced by an editor is much less likely to be identified and corrected than an error introduced by a writer.
First, do no harm.
*One day at The Cincinnati Enquirer, a reporter was striding about the newsroom, within earshot of the copy desk, complaining bitterly that his article for that day's editions had been brutally trimmed (to fit the available space). So I said, "As the infant son of observant Jews, Jesus was circumcised several days after birth. Who are you not to get cut?"
On my own account, I once trudged back to the features department to complain that one of my book reviews had been edited to near-unintelligibility. As I spoke, I saw two features writers smirking and realized that (1) the editor I was talking to was a well-meaning dolt, (2) that I should have expected no better from the editing, (3) that there was no remedy for past editing and faint hope for future efforts, and (4) that I was making a fool of myself. Since that day, and it has been nearly thirty years, I have never complained about the cutting of my copy.
**Injury induced by medical treatment.