Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This comic is a graph joke plotting "Difficulty of Proving a Mathematical Fact" on the y-axis against "Obviousness of That Fact" on the x-axis. The curve shows that as a mathematical fact becomes more obvious, it actually becomes exponentially harder to prove rigorously. The labeled data point at the extreme end reads: "Prove that a set of elements contains the elements it contains."

The joke reflects a real phenomenon in mathematics and logic. Statements that seem trivially, self-evidently true -- like "a set contains its own elements" -- often require surprisingly deep and careful formal proof. In foundational mathematics and set theory, establishing things that seem like they should need no proof at all (tautologies, basic axioms, identity properties) can require elaborate logical frameworks. The comic humorously captures the frustration of mathematicians who must rigorously demonstrate what everyone already intuitively knows to be true.