Lessing attended university in Berlin and Bonn, after which he taught History of Decorative Arts in Berlin. In 1872 he was responsible for a large exhibition of decorative art in Berlin, which featured objects from the royal collection as well as privately held items, under the patronage of Crown Prince Frederick. The success of this exhibition led to the founding of the Museum of Decorative Arts in Berlin, which Lessing led until his death in 1908.
In 1894 he published his Neue Wege (New Ways) article in the journal Kunstgewerbeblatt, praising new materials in architecture. 
He was buried in the Jewish Cemetery in Friedhof Schönhauser Allee. He was the grandfather of photographer Marianne Breslauer.