In 1932 Whitney showed that a graph $G$ with order $n\geq 3$ is 2-connected if and only if any two vertices of $G$ are connected by at least two internally-disjoint paths. The above result and its proof have been used in some Graph Theory books, such as in Bondy and Murty's well-known Graph Theory with Applications. In this note we give a much simple proof of Whitney's Theorem.
 Bondy, J. A., Murty, U. S. R.: Graph Theory with Applications
. Elsevier, New York (1976). MR 0411988