“Some critics have seen these [The Black on Black paintings] paintings as Rothko’s pointed reminder that there was more to his work than lyric color—that his real subject was (as he had declared in 1943) the “tragic and timeless.” Others have seen them as tokens of the illness and depression that began to plague Rothko in the 1960s, even as harbingers of his suicide at the end of the decade.

But does black = tragedy and despair? While it does absorb more light than any other color, it is not just a void. Depending upon the quality of paint and its application, as well as shifting angles of light, the blacks here can look like steel or velvet, silver screens or black holes. Other colors lie in wait under a surface or peek around an edge. But to notice all this takes time: unless we look at the paintings slowly, we will not see what Rothko called their “inner light.”“

- From the National Gallery of Art Website