"the most tragic moment in the Tale comes in II 323 ff. ['The Stairs of Cirith Ungol'] when Sam fails to note the complete change in Gollum's tone and aspect. 'Nothing, nothing', said Gollum softly. ‘Nice master!'. His repentance is blighted and all Frodo's pity is (in a sense) wasted. Shelob's lair became inevitable."