Possible Clues:

• One is not one
• 2 perhaps, yet more unfeeling
• It indicates the previous clue, say, is less sensitive than before
• Two perhaps yet further up the scale of insensitivity
• What comes before or after this clue is still less sensitive
• Two will go into it with still less feeling
• It takes two at least to make one have less feeling than before
• To start with, two may have even less feeling for this