  For each simply-laced Dynkin graph $\Delta$ we realize the simple complex Lie
algebra of type $\Delta$ as a quotient algebra of the complex degenerate
composition Lie algebra $L(A)_{1}^{\mathbb{C}}$ of a domestic canonical algebra
$A$ of type $\Delta$ by some ideal $I$ of $L(A)_{1}^{\mathbb{C}}$ that is
defined via the Hall algebra of $A$, and give an explicit form of $I$.
Moreover, we show that each root space of $L(A)_{1}^{\mathbb{C}}/I$ has a basis
given by the coset of an indecomposable $A$-module $M$ with root easily
computed by the dimension vector of $M$.
