[QUOTE=Don’t fight the hypothetical]
Gotta go with = gun. With that you can get anything else you need , no?
[/QUOTE]
Can you sleep with one eye open?
The answer to this question depends on the nature of the collapse. Are we talking about a temporary failure of civil authority (during, say, a natural disaster or localized attack), a broader collapse of governance and ready distribution of industrial goods (civil war, economic collapse, et cetera), or a long-term atavism in society as a whole from some kind of massive die-off that drops population density below that needed to sustain an industrial and transportation infrastructure, a la George Stewart’s Earth Abides?
In the case of a short term failure, stockpiling basic goods and dry semi-perishables for your own use is the best bet. A 30 day stockpile of food and necessities (including basic first aid supplies and water filtration) will fit in a large closet. Animals (except for guard animals) will probably be more of a liability than an asset in general. Weapons, especially ranged weapons, may be very useful for defense against marauders and opportunists, but an arsenal of weapons will be of little use in a real siege; mobility and concealment in the face of aggression is generally the best policy, especially as even a non-complicated injury from combat may result in infection and death.
In the second case, a broader collection of tools and means to manufacture basic machines for agricultural and construction projects in addition to more extended and preserved diet staples. Beasts of burden and food producing animals (especially for producing dairy and honey) are a definite asset if you can protect them from predators, human or otherwise. Trade goods, including tobacco, distilled alcohol, coffee, textiles, non-perishable pharmaceuticals, mechanical fasteners, ammunition, fuel, et cetera will be valuable, but so will skills and references for repairing and improvising salvaged machinery, and references therefore. Weapons are likely to be less important for survival than raw numbers; your best bet for security and survival is to ally with larger groups.
In the third case, anything that requires lubrication, external power or fuel, or is sensitive to corrosion or rough handling will fail sooner or later, usually right when you need it the most. You would want to translate to pre-Industrial means of self-sufficiency rather than stockpiling food staples and supplies for the long haul, including means and methods to preserve food, construct habitats from natural supplies and simple methods, adopt a hunter/gatherer/gardener approach to food procurement, et cetera. Literacy and the knowledge of complex machinery will be less important than interpersonal/political, and knowledge of edible/medicinal plants, primitive survival skills, et cetera. Work animals will be necessary for large scale trade or broad agriculture, but carry their own costs of injury, infection, defending against predators, et cetera.
I can’t see any situation in which an encyclopedia, with its highly generalized knowledge, would be particularly valuable. However, basic construction engineering, primitive medicine, and botanical references might be very useful. Books and illustrations of all kinds would be valuable as the only means of storied entertainment.
Stranger