Book that summarizes mathematics in a way appropriate for preservation for future generations Maybe this question is a bit silly, but I'll take that risk and ask it anyway. Recently, I've been thinking about making a time capsule to be hidden in the ground and (hopefully) not be opened for at least a few centuries.
Naturally, storage space will be quite limited, and so I want to pick out items that in as good a way as possible will represent the very essence of humanity (and perhaps even be of some practical use, should society have completely broken down). To me, this is mathematical and scientific advancement.
I would therefore like to hear some suggestions for one, or possibly two, books which summarize most of mathematics at its current stage. Preferably, the book(s) should feature some proofs, but most of all it(they) should be a comprehensive collection of mathematical knowledge thus far.
I have considered something like a mathematical encyclopedia, but in my experience, the level of technicality is often quite low in these, and I want something with precise statements of mathematical results.
Thanks in advance!
 A: What about the Princeton Companion to Mathematics?
A: I'm not sure if I understood well your suggestion but if we have to preserve the Math for some long time, in my opinion, for sure, The Elements, by Euclides, must be there.
A: I'm aware that you want something encyclopedic, but if you really want to capture the spirit of mathematics, it's hard to do better than this poem by mathematician par excellence William Rowan Hamilton, concerning his discovery of quaternions (which eventually lead to vectors, matrices, tensors, linear algebra, differential geometry, Lie group theory, etc.):
THE TETRACTYS
Or high Mathesis, with her charm severe,
Of line and number, was our theme; and we
Sought to behold her unborn progeny,
And thrones reserved in Truth's celestial sphere:
While views, before attained, became more clear;
And how the One of Time, of Space the Three,
Might, in the Chain of Symbol, girdled be:
And when my eager and reverted ear
Caught some faint echoes of an ancient strain,
Some shadowy outlines of old thoughts sublime,
Gently he smiled to see, revived again,
In later age, and occidental clime,
A dimly traced Pythagorean lore,
A westward floating, mystic dream of FOUR.
