Combinatorics of Bricard’s octahedra

We re-prove the classification of flexible octahedra, obtained by Bricard at beginning XX century, means combinatorial objects satisfying some elementary rules. The explanations these rules rely on use a well-known creation modern algebraic geometry, moduli space stable rational curves with marked points, for description configurations graphs sphere. Once one accepts and rules, becomes (though not trivial) can be enjoyed without need very deep background topic.