In this Portrait of Michelangelo there are basically
two light areas;
the face and the left hand.
The emphasis on the hand alludes to the manual strength necessary in the art of the sculptor. Michelangelo always considered himself first and foremost a sculptor.
His favorite subject matter was the male human body in motion. At this time in his life he had sculpted the famous image of David. He had been commissioned after that to make a tomb for Pope Julius. In 1508 the Pope summoned him to Rome, from Florence, to paint the Sistine Chapel ceiling. Michelangelo was hesitant to go but couldn't say no to the Pope.