He developed, during his writing, a black speck or 'floater' in his left eye. In January 1836 his 'friend, the black speck' is still with him, and he tells John that both Mill and Leigh Hunt have the same trouble, so must have raised the subject with them. He asks John not to mention the speck in his reply, or to do so in German, so that their mother, who will read the letter, may not be troubled. As usual he blames it on liver and bile, but also relates it to his intensive work on the French Revolution. It was almost certainly a posterior detachment of the vitreous, a common disorder of the ageing eye.
Health continues to be the ever-interesting topic in the family correspondence.
His health varies from week to week. In December Carlyle doses himself twice with senna and makes himself sick. He complains of 'right-sided, thumping, headache', which he treats with a long walk followed by Madeira wine. In January 1837 he completed French Revolution , and Jane made him a bread pudding to celebrate. Colds continue in February and he reports to brother John that their mother has had a 'biliary complaint' for three days.