Symptoms of mercury poisoning include excessive timidity, diffidence, increasing shyness, loss of self-confidence, anxiety, and a desire to remain unobserved and unobtrusive. WHAT? Nothing MAD about all that. So then … when is a Hatter NOT Mad? When he is FURIOUS. Read more about madness at Bleeding Cool:Symptoms of mercury poisoning include excessive timidity, diffidence, increasing shyness, loss of self-confidence, anxiety, and a desire to remain unobserved and unobtrusive. WHAT? Nothing MAD about all that. So then … when is a Hatter NOT Mad? When he is FURIOUS.