Complex sentence: He is a habitual self portraitist producing Rembrandt inspired self portraits that mark his passing years, His protraits from 1915 to the end of the 1920s are a gallery of the leading expressionist and Dada writers and poets.
Split into simpler sentences: He is a habitual self portraitist producing a remarkable series of Rembrandt inspired self portraits that provide a vivid illustration to his passing years. His portraits from 1915 to the end of the 1920s are a gallery of the leading expressionist and Dada writers and poets.