posthumous meaning?

"Carl Becker has pointed out the 'uses of posterity' for the philosophes of the eighteenth century: the judgment of the court of history provided a kind of secular immortality for those who had worked long and earnestly to further the good of the human spirit. Those nineteenth-century intellectuals who theorized about their own role also needed to be remembered, needed to be able to project the approval of their sub-group into the future, and to console themselves with the thought that (however little acclaim they might receive in their generation) they would be remembered as those who had in their day had charge of the light."
posthumous meaning?
-- The Idea of the Clerisy in the Nineteenth Century, Ben Knights, 1978, p. 8.