It means what it means, "freely" pulls its own weight. I didn't say "readily" accessible. Torrents could be viewed as "readily" accessible but it couldn't be viewed as "freely" accessible because at the very least you bear the guilt of theft. Library books are "freely" accessible, and if somehow the training involved checking out books and returning them digitally, it should be fine. If it is free to read into neurons it is free to read into neural systems. If payment for reading is expected then it isn't free.