In the short story The Planet of the Dead by Clark Ashton Smith, I would like to understand the meaning of "half-primitive vigor":
He had lived as an intellectual sybarite; and by virtue of a half-primitive vigor, had not yet fallen upon the spiritual exhaustion and desolation, the dread implacable ennui of racial senescence, that marked so many of his fellows.
There are several meanings in the dictionary but none make really sense to me with "half".