Arthur Asher Miller (October 17, 1915 - February 10, 2005) was an American playwright, essayist, and figure in twentieth-century American theater. Among his most popular plays are All My Sons (1947), Death of a Salesman (1949), The Crucible (1953) and A View from the Bridge (1955, revised 1956). He also wrote several screenplays and was most noted for his work on The Misfits (1961). The drama Death of a Salesman has been numbered on the short list of finest American plays in the 20th century alongside Eugene O'Neill's Long Day's Journey into Night and Tennessee Williams's A Streetcar Named Desire.

In 1940, Miller married Mary Grace Slattery. The couple had two children, Jane and Robert (born May 31, 1947). Miller was exempted from military service during World War II because of a high school football injury to his left kneecap. That same year his first play was produced; The Man Who Had All the Luck won the Theatre Guild's National Award. The play closed after four performances with disastrous reviews.  In 1947, Miller's play All My Sons, the writing of which had commenced in 1941, was a success on Broadway (earning him his first Tony Award, for Best Author) and his reputation as a playwright was established. Years later, in a 1994 interview with Ron Rifkin, Miller said that most contemporary critics regarded All My Sons as "a very depressing play in a time of great optimism" and that positive reviews from Brooks Atkinson of The New York Times had saved it from failure.  In 1948, Miller built a small studio in Roxbury, Connecticut. There, in less than a day, he wrote Act I of Death of a Salesman. Within six weeks, he completed the rest of the play, one of the classics of world theater. Death of a Salesman premiered on Broadway on February 10, 1949, at the Morosco Theatre, directed by Elia Kazan, and starring Lee J. Cobb as Willy Loman, Mildred Dunnock as Linda, Arthur Kennedy as Biff, and Cameron Mitchell as Happy. The play was commercially successful and critically acclaimed, winning a Tony Award for Best Author, the New York Drama Circle Critics' Award, and the Pulitzer Prize for Drama. It was the first play to win all three of these major awards. The play was performed 742 times.  In 1949, Miller exchanged letters with Eugene O'Neill regarding Miller's production of All My Sons. O'Neill had sent Miller a congratulatory telegram; in response, he wrote a letter that consisted of a few paragraphs detailing his gratitude for the telegram, apologizing for not responding earlier, and inviting Eugene to the opening of Death of a Salesman. O'Neill replied, accepting the apology, but declining the invitation, explaining that his Parkinson's disease made it difficult to travel. He ended the letter with an invitation to Boston, a trip that never occurred.

Using a quote from the above article, answer the following question: what did critics think of his work?
"a very depressing play in a time of great optimism" and that positive reviews from Brooks Atkinson of The New York Times had saved it from failure.