* Physician: His primary profession and the focus of his most impactful work.
* Naturalist: He had a keen interest in the natural world, observing and documenting plants and animals.
* Poet: He wrote poetry, though none was published during his lifetime.
* Artist: He was a skilled artist and created many sketches and drawings, including some of his patients.
Therefore, it's impossible to pinpoint one single favorite subject. His curiosity and dedication to science likely fueled his interest in various fields.