I have sometimes struggled to comb through several decades of legal research (as well as science and philosophy research) on my iMac 4tb hard drive. I’ve used Apple Spotlight’s multi-faceted document search function over the years and it is often quite helpful. Today, however, I learned about FoxTrot Professional Search. It is incredibly powerful, allowing you to pinpoint documents, images, spreadsheets and mail in dozens of ways, including proximity searches and tailor-made search strings with exceptions. You can apply complicated search requests to multiple indices on your main HD, as well as external drives (I’ve got another 3+ TB of data on my external drive. I’ve been exploring the parameters of FoxTrot for a couple of hours now and I highly recommend it. $100 per workstation. I hope this helps somebody out there . . .