Algebra (n.) is math having sex with the alphabet.
Algebra (n.) is like a recipe written for an ingredient you have not bought yet.
Algebra (n.) is like a scale, whatever you take from one side you owe the other.
Algebra (n.) is the promise that an unknown will behave itself while you move it around
Geometry (n.) is that part of universal mechanics which accurately proposes and demonstrates the art of measuring.
Geometry (n.) is a technique born in Egypt, where the inundations of the Nile, by obliterating the bounds of the fields, made the people invent exact measures to distinguish every man's land from his neighbor's.
Geometry (n.) is a clear profile hidden in the shadows
Geometry (n.) is the key to reading the book of the universe; a book written in the mathematical language where the symbols are triangles, circles, and other geometrical figures, without the help of which it is impossible to conceive a single word of it, and without which one wanders in vain through a dark labyrinth.
Incompleteness theorem (n.) is Gödel's proof that any consistent system rich enough for arithmetic contains true statements it cannot prove.
The Incompleteness theorem (n.) states that if you can derive everything that is true from a system, you will also be able to derive things that are false, but in a consistent system, you can't derive anything that is false.
The Incompleteness theorem (n.) is that any formal system that you can set up can have the property of completeness, or the property of consistency, but not both.
Probability (n.) is not fact — A thousand probabilities do not make one fact.
Probability (n.) is as good as it gets — A reasonable probability is the only certainty.
Probability (n.) is never certain — Fate laughs at probabilities.
Probability (n.) is paradoxically structured in that it is probable that many things will happen contrary to probability.