The title of
Bertrand Russell and
Alfred North Whitehead's mammoth
1912 attempt to bring all
arithmetic under a
formal axiom system.
One curious aspect of
Principia Mathematica is that it does not prove
1 + 1 = 2 until page 362.
The name
Principia Mathematica is also used to refer to Sir
Isaac Newton's landmark work
Principia Mathematica Philosophiae Naturalis.