H.p. Lovecraft said this quote
“ A certain atmosphere of breathless and unexplainable dread of outer, unknown forces must be present; and there must be a hint, expressed with a seriousness and portentousness becoming its subject, of that most terrible conception of the human brain - a malign and particular suspension or defeat of those laws of Nature which are our only safeguard against the assaults of chaos and the daemons of unplumbed space .... Therefore we must judge a weird tale not by the author's intent, or by the mere mechanics of the plot; but by the emotional level which it attains at its least mundane point... The one test of the really weird is simply this - whether or not there be excited in the reader a profound sense of dread, and of contact with unknown spheres and powers; a subtle attitude of awed listening, as if for the beating of black wings or the scratching of outside shapes and entities on the known universe's utmost rim. ”