All that Danforth has ever hinted is that the final horror was a mirage. It was not, he declares, anything connected with the cubes and caves of those echoing, vaporous, wormily-honeycombed mountains of madness which we crossed; but a single fantastic, demoniac glimpse, among the churning zenith-clouds, of what lay back of those other violet westward mountains which the Old Ones had shunned and feared.  
    It is very probable that the thing was a sheer delusion born of the previous stresses we had passed through, and of the actual though unrecognized mirage of the dead transmontane city experienced near Lake's camp the day before; but it was so real to Danforth that he suffers from it still.