This must be the self portrait described by the artist's son John in 1830. In the winter of 1795 he painted a head of himself, which, though slight, and not entirely finished, being painted at once, shows uncommon power of execution; the likeness also is strong, but there is a certain expression of languor that indicates the approach of disease. . . . It is remarkable that it is painted without spectacles, though he had been in the habit of using glasses for many years. (https://metmuseum.org/art/collection/search/437504)