Since I'm in the process of moving my office, I've been taking time to do something that's needed to be done for quite a while: cleaning out my files. Somewhere around 2007 or so, I made the switchover to keeping PDFs as my primary filing system, with paper copies when needed. There was a transitional period, which I ended up splicing together by checking through my recent printed copies and backfilling those into my digital archive, but after that, it was all digital. (For the record, I'm still using Zotero for that purpose, although there are several equally valid alternatives, both commercial and freeware).
But I still had a pretty massive filing cabinet full of stuff, and I let that remain undisturbed, even though I knew some of it was surely junk. Only when I started digging into it did I realize just how much of it was little more than that. I'd estimate that I've thrown at least 80% of my files into the recycling bin, an act that would have made me uneasy only a few years ago, and horrified me in, say, 2004. It was easier than I thought, though.
That's because the folders easily fell into several broad categories. In the medical/biological sections of the cabinet, there were "Topics I'm Unlikely to Revisit - And When I Do, It Won't Be With These References". Those went right into the recycling bin. And there were "Topics I May Well Revisit, But When I Do, It Won't Be With These References". Those, after a glance through their contents, went into the bin as well. These were folders on (for example) disease areas that I've worked on in the past, and might conceivably work on again, but a folder full of ten-year-old biomedical articles is not that useful compared to the space it takes up and the trouble it takes to move it. And if that sounds borderline to you, how about the ones that hadn't been updated since the late 1990s? Junk. Nothing in the literature goes out of date faster than a state-of-current-disease-research article.
Moving to the chemistry folders, I was quickly surprised at how many of those I was throwing away as well. The great majority of the printed papers I kept were chemistry ones, but the great majority of what I started out with went into the recycling bin anyway. Digging through them was, in many cases, a reminder of what keeping up with the literature used to be like, back in the day. It was a time when if you found a useful-looking paper, you copied it out and put it in your files, because there was no telling when or if you'd be able to find it again. If you were one of the supremely organized ones, you drew a key reaction or two on an index card and filed that according to some system of your own devising - that's before my time, but I saw people doing that back when I was a grad student. The same sort of pack-ratting persisted well into the 1990s, though, but eroded in the face of better access to Chemical Abstracts (and the rise of competing databases). Finding that reaction, or others like it, or even better references than the ones you knew about, became less and less of a big deal.
So in my files, over in the section for "Synthesis of Amines", there was a folder on the opening of epoxides by amines. And in it were several papers I'd copied in the late 1980s. And some printed-out hits from SciFinder searches in about 1993. And a couple of reactions that I'd seen at conferences, and a paper from 1997 showing how you could change the site of ring opening, sometimes, with some systems. Into the bin it went, despite the feeling (not an inaccurate one) that I was throwing away work that I'd put into assembling all that. But if I find myself wanting to run such a reaction, I can probably set something up that'll work fairly well, and if it doesn't, I can probably find a review article (or two) where someone else has assembled the previous literature.
One of the biggest problems with my chemistry files, I realized, was the difficulty of searching them. I'd gotten used to the world of SciFinder and Reaxsys and Google and PubMed, where information can be called up any way you like. File folders, though, do not speak of their contents. Unless you have the main points of that content committed to memory, you have to open them up and flip through them, hoping for something relevant to pop up. I can well remember doing that in the early 1990s with some of these very folders ("Hmm, let's see what methods I have for such-and-such"), but that style of searching disappeared many years ago. You can now see what methods everyone has, and quickly find out what's been added to the pile since the last time you looked. Younger researchers who've grown up in that world may find it odd that I'm pointing out that water is wet, but my earliest file-cabinet folders were started in another time. File folders are based on tagging (and in its purest form, a physical label), and I agree with people who say that the ability to search is more important and useful than the ability to tag.
So, what did I keep? Folders on specialized topics that I recalled were very difficult to assemble, in a few cases. Papers that I know that I've referred to several times over the years. Papers that refer directly to things that I'm currently working on. Some stuff that's so old that it falls under the category of memorabilia. And finally, papers on more current topics that I want to make sure that I also have in digital form, but didn't have time to check just now. But that three-inch-thick collection of nuclear receptor papers from 2000-2002? The papers on iron dienyl reagents that I copied off during a look at that chemistry in 1991, and never had a need to refer to after about ten days? A folder of reductive amination conditions from the late 1980s? Into the big blue bin with all of it.