Let $G$ be a complex semi-simple Lie group. Then any subgroup $P$ of $G$ containg a Borel subgroup $B$ is called parabolic. Parabolics are classified in the following manner. Let $\fr g$ be the Lie algebra of $G$ , $\fr h$ the unique Cartan subalgebra contained in $\fr b$ , the algebra of $B$ , $R$ the set of roots corresponding to this choice of Cartan, and $R^+$ the set of positive roots whose root spaces are contained in $\fr b$ and let $\fr p$ be the Lie algebra of $P$ . Then there exists a unique subset $\Pi_P$ of $\Pi$ , the base of simple roots associated to this choice of positive roots, such that $\{\fr b,\fr g_{-\alpha}\}_{\alpha\in\Pi_P}$ generates $\fr p$ . In other words, parabolics containing a single Borel subgroup are classified by subsets of the Dynkin diagram, with the empty set corresponding to the Borel, and the whole graph corresponding to the group $G$ .