By BROOKS ATKINSON

With the production of "Long Day's Journey Into Night" at the Helen Hayes last evening, the American theatre acquires size and stature.

The size does not refer to the length of Eugene O'Neill's autobiographical drama, although a play three and three quarter hours long is worth remarking. The size refers to his conception of theatre as a form of epic literature.

"Long Day's Journey Into Night" is like a Dostoevsky novel in which Strindberg had written the dialogue. For this saga of the damned is horrifying and devastating in a classical tradition, and the performance under José Quintero's direction is inspired.

Twelve years before he died in 1953, O'Neill epitomized the life of his family in a drama that records the events of one day at their summer home in New London, Conn., in 1912. Factually it is a sordid story about a pathologically parsimonious father, a mother addicted to dope, a dissipated brother and a younger brother (representing Eugene O'Neill) who has TB and is about to be shipped off to a sanitarium.

Roughly, those are the facts. But the author has told them on the plane of an O'Neill tragedy in which the point of view transcends the material. The characters are laid bare with pitiless candor. The scenes are big. The dialogue is blunt. Scene by scene the tragedy moves along with a remorseless beat that becomes hypnotic as though this were life lived on the brink of oblivion.

"Long Day's Journey Into Night" could be pruned of some of its excesses and repetitions and static looks back to the past. But the faults come, not from tragic posturing, but from the abundance of a great theatre writer who had a spacious point of view. This summing-up of his emotional and artistic life ranks with "Mourning Becomes Electra" and "Desire Under the Elms," which this department regards as his masterpieces.

Like those dramas, it comes alive in the theatre. Although the text is interesting to read between covers, it does not begin to flame until the actors take hold of it. Mr. Quintero, who staged the memorable "The Iceman Cometh" in the Village, has directed "Long Day's Journey Into Night" with insight and skill. He has caught the sense of a stricken family in which the members are at once fascinated and repelled by one another. Always in control of the turbulence of the material, he has also picked out and set forth the meaning that underlies it.

The performance is stunning. As the aging actor who stands at he head of the family, Fredric March gives a masterly performance that will stand as a milestone in the acting of an O'Neill play. Petty, mean, bullying, impulsive and sharp-tongue, he also has magnificence--a man of strong passions, deep loyalties and basic humility. This is a character portrait of grandeur.

Florence Eldridge analyzes the pathetic character of the mother with tenderness and compassion. As the evil brother, Jason Robards Jr., who played Hickey in "The Iceman Cometh," gives another remarkable performance that has tremendous force and truth in the last act. Bradford Dillman is excellent as the youngest brother--winning, honest, and both callow and perceptive in his relationship with the family. Katherine Ross plays the part of the household maid with freshness and taste.

All the action takes place inside David Hays excellent setting of a cheerless living-room with dingy furniture and hideous little touches of unimaginative décor. The shabby, shapeless costumes by Motley and the sepulchral lighting by Tharon Musser perfectly capture the lugubrious mood of the play.

"Long Day's Journey Into Night" has been worth waiting for. It restores the drama to literature and the theatre to art.