Whoever decided to stage Eugene O'Neill's grimmest family drama, "Long Day's Journey Into Night," in rotating repertory with his lightest family comedy, "Ah, Wilderness!" with the same two brilliant stars, Colleen Dewhurst and Jason Robarts, has the same "touch of the poet" as the playwright.

The plays are two sides of the same drama and are being staged this summer at the Neil Simon Theater in celebration of the 100th anniversary of the birth of O'Neill. The productions have come to Broadway as part of the First New York International Festival of the Arts from the Yale Repertory Theater in New Haven, Conn.(Editor's note: "Ah, Wilderness!" is coming to at least two Utah stages during the 1988-89 season - Weber State College, Nov. 10-19 and the Heritage Theater in Perry, Jan. 20-Feb. 11.)

The plays represent O'Neill's nightmare and his wish fulfillment fantasy. "Journey" deals with the playwright's perception of the tragic reality of his own family. "Wilderness" represents the O'Neill family as he wished it had been.

This fascinating twinship of the darker and lighter sides of the same family story should both be seen to sense the full dimension of America's most acclaimed and awarded playwright. Although the comedy outshines the tragedy in casting, production and direction, together they form an indelible dramatic whole - a sense of life in its fullest spectrum.

The penny-pinching actor-father of "Journey," who keeps the family sitting in the dark to save on electricity, is the generous, affectionate publisher-father of "Wilderness."

The dissolute older brother, Jamie, of the former play, is just a normal, fun-loving gadabout with a possibly dissolute buddy in the latter. The poetic, romantic younger son, Edmund, of the tragedy, who is the playwright's vision of himself, is Richard, the successful suitor of his dream girl in the comedy.

And, most interesting of all, the drug-addicted mother of "Journey," whose personal tragedy is the centertpiece of the family tragedy, is the warm, loving, hovering mother of "Wilderness." Both women share some of the same personality traits, such as the tiny zaps they send out at their husbands, although Mary Tyrone's in "Journey" are far more vicious than Essie Miller's in "Wilderness."

Written seven years before "Journey," "Wilderness" is perhaps its precursor - O'Neill testing the waters of portraying his family as he wishes they had been before diving into the depths of portraying them as they really are.

Both Robards and Dewhurst appear to be far more comfortable in the roles in "Wilderness" than they are in "Journey."

Although it is difficult at first to ignore Dewhurst's shimmering, innate strength in the passive-aggressive role of Mary Tyrone, she is ultimately very convincing and very moving as the victimized wife and mother who manipulates her family through guilt. The actress is not a woman who would bleat when she could roar, yet she manages to whimper her endless implied accusations and make us believe them.

Robards plays the actor, James Tyrone, sympathetically, not as the bully, tyrant, cheapskate his sons see him to be, but more as a misunderstood man, whose loving intentions are thwarted by his own past.

In this family of secrets, Mary Tyrone is trying to hide the fact that she is addicted to morphine. James Tyrone is trying to hide the fact the Edmund has tuberculosis. And everybody is trying to hide their bitter hopelessness which spills out in drams and dregs, until they drink, when it gushes out in quarts.

By contrast, the basic set of a summer cottage living room with the long front porch beyond, which is drab and dreary in Ben Edwards' design for "Journey" is sun-lit, plant-filled and vivid with bright fabrics in Michael H. Yeargan's design for "Wilderness." In addition set designer Yeargan has created a properly seedy barroom for the comedy's scene of Richard's fall from grace and a perfectly lovely strip of beach for his reunion with his dreamgirl, Muriel.

"Wilderness" offers George Hearn, late of Broadway's "La Cage aux Folles," one of the theater's juiciest roles as the unreconstructed reprobate, Uncle Sid. He is superb coming home drunk from the Fourth of July picnic, insisting on eating his soup with a fork and his lobster with a shell.