I've been looking through my library, acutely aware of certain deficiencies in a number of areas. I've a few decent references on human medicine, but am lacking enough good ones on veterinary medicine... I might have to look at some of the second-hand stores around universities for both.
Of course, half of medicine seems to be prevention, maybe a third trauma. I'm speaking as someone with only a small amount of medical training, so perhaps I'm not entirely appraised - but considering how much space in books tends to be devoted to hygiene, perhaps not. This doesn't take into account advances in many fields, specialist stuff...
Damn it... I am a generalist, not a specialist. I can do a lot, but... Jack of all trades, Master of none.
Far too much to gather... Oh, for some people to gather into the fold. I will be happy if I can learn enough blacksmithing soon to make a few things, but I need someone who makes it at least a serious hobby.
Don't get me wrong, I'm doing more than just buying books... But if you have limited time to learn every skill... And maybe, perhaps, avoiding the pitfalls of lost technology...