By sanctioning promiscuity among married people in his newest play, John van Druten universalizes the idea presented in his "The Voice of the Turtle," which sanctioned it among the unmarried. Now everybody can have affairs.

The parallel between the two plays goes deeper, however. In "The Voice of the Turtle" van Druten raised the moral level of his ideas by having his promiscuous young couple fall in love in the end. In "The Mermaids Singing" he takes the objectionable crackle out of his created situation by dramatizing an affair which doesn't come off. "The Voice of the Turtle" was carefully cast, brilliantly written, and subtly directed. So is "The Mermaids Singing," but, as a play, the former remains much the superior of the two.

Neither the hero of "The Mermaids Singing," a prominent playwright, nor the heroine, a sweet young thing, are likeable or believable people. The height of their implausibility comes, properly enough, at the second act climax. The girl runs off in the middle of the night and tells the married playwright she is in love with him, that anything he wishes to do is all right with her, and the sooner he does it, the better. The playwright, a man of morals, tells her to go home and wait while he makes up his mind. And it doesn't take him long to conclude that the girl's proposition has its advantages. Why he doesn't take her up on it eventually, makes a complicated story.

If these people were not obviously the well-meaning, intelligent pair van Druton has intended, irony might save the play. As it is, "The Mermaids Singing" is an empty if craftsmanlike display of immorality.