  We study the model for holographic dark energy in a spatially closed
universe, generalizing the proposal in hep-th/0403127 for a flat universe. We
provide independent arguments for the choice of the parameter $c=1$ in the
holographic dark energy model. On the one hand, $c$ can not be less than 1, to
avoid violating the second law of thermodynamics. On the other hand,
observation suggests $c$ be very close to 1, it is hard to justify a small
deviation of $c$ from 1, if $c>1$.
