  We give a definition of quarternion Lie algebra and of the quarternification
of a complex Lie algebra. By our definition gl(n,H), sl(n,H), so*(2n) and sp(n)
are quarternifications of gl(n,C), sl(n,C), so(n,C) and u(n) respectively. Then
we shall prove that a simple Lie algebra admits the quarternification. For the
proof we follow the well known argument due to Harich-Chandra, Chevalley and
Serre to construct the simple Lie algebra from its corresponding root system.
The root space decomposition of this quarternion Lie algebra will be given.
Each root space of a fundamental root is complex 2-dimensional.
