If you've ever discussed historical hockey players online, particularly in the context of comparing them to modern players, you may have come across the following comment, or something similar: "You can't really compare players from the past with those of today, because you didn't actually see the older players play." Similarly, when constructing some list of all-time something-or-others, someone will invariably say something like "I can only comment on the players I actually saw play."
In the context of hockey history, I find this type of comment baffling. History is not defined as "what you have witnessed personally." In studying the history of the game, of course you will encounter people and events that you have no direct personal experience with. To suggest that you can only make educated comments about things you have seen yourself is counter-historical. History involves the study of, well, history - things in the past, oftentimes beyond the memory of any living person, much less yourself. But events of the past do not suddenly become unknowable when the last direct witness passes - you just have to study the record in order to know it.
If you limit yourself to what you have seen yourself, I suppose you might feel more secure in the knowledge you do have (although the fact that you're relying on human memory has problems of its own). But let me tell you, if you choose not to study the history of the game because you can't "know" it the way you can with modern hockey, you're doing yourself a disservice. The history of the game is fascinating, and well-worth the effort of studying it.
Of course, if you're here reading this, you probably already agree.