Robert Schumann (1810-1856) is variously noted for being married to the most beautiful woman in the world (apart from Harriet Smithson and George Sand), being as mad as a penguin and not being able to orchestrate for toffee.
His lack of orchestral technique did not hold him back from composing 4 Symphonies (which notably get worse instead of better as they ascend chronologically) a Cello Concerto (underrated and quite a few hummable tunes in there) and a very good Piano Concerto which conductor's cannot conduct the last movement of because it has both 3 beats in a bar, one beat per bar and sometimes syncopation of 2+2+2 over three bars.
His Piano music is however something else. It is so well written for the Piano that no normal Piano student can play it. You have to be a genius to sit down in front of Schumann's Piano music. It is of an exceptional quality. Butterflies go into your stomach at the thought of it. A Carnival procession passes by your front door and your next-door-neighbour virtually Abeggs you not to play it any more.
Schumann also wrote various songs (leider, from the German for "unfortunately") and chamber music (kukumbermusik) normally for fewer than two clarinets.