“Take care,” warns The Old Man in that most simply touching of Maeterlinck’s plays, Interieur; “we do not know how far the soul extends about men.”  It is a subtle and characteristic saying, and it might have been used by the dramatist as a motto for his Pelleas et Melisande; for not only does it embody the central thought of this poignant masque of passion and destiny, but it summarizes Maeterlinck’s attitude as a writer of drama.  “In the theatre,” he says in the introduction to his translation of Ruysbroeck’s l’Ornement des Noces Spirituelles, “I wish to study ... man, not relatively to other people, not in his relations to others or to himself; but, after sketching the ordinary facts of passion, to look at his attitude in presence of eternity and mystery, to attempt to unveil the eternal nature hidden under the accidental characteristics of the lover, father, husband....  Is the thought an exact picture of that something which produced it?  Is it not rather a shadow of some struggle, similar to that of Jacob with the Angel?” Art, he has said, “is a temporary mask, under which the unknown without a face puzzles us.  It is the substance of eternity, introduced ...by a distillation of infinity.  It is the honey of eternity, taken from a flower of eternity.”  Everywhere, throughout his most deeply characteristic work, he emphasizes this thought—­he would have us realize that we are the unconscious protagonists of an overshadowing, vast, and august drama whose significance and denouement we do not and cannot know, but of which mysterious intimations are constantly to be perceived and felt.  The characters in his plays live, as the old king, Arkel, says in Pelleas et Melisande, like persons “whispering about a closed room,” This drama—­at once his most typical, moving, and beautiful performance—­swims in an atmosphere of portent and bodement; here, as Pater noted in the work of a wholly different order of artist, “the storm is always brooding;” here, too, “in a sudden tremor of an aged voice, in the tacit observance of a day,” we become “aware suddenly of the great stream of human tears falling always through the shadows of the world.”  Mystery and sorrow—­these are its keynotes; separately or in consonance, they are sounded from beginning to end of this strange and muted tragedy.  It is full of a quality of emotion, of beauty, which is as “a touch from behind a curtain,” issuing from a background vague and illimitable.  One is aware of vast and inscrutable forces, working in silence and indirection, which somehow control and direct the shadowy figures who move dimly, with grave and wistful pathos, through a no less shadowy pageant of griefs and ecstasies and fatalities.  They are little more than the instruments of a mysterious will, these vague and mist-enwrapped personages, who seem always to be unconscious actors in some secret and hidden drama whose progress is concealed behind the tangible drama of passionate and tragic circumstance in which they are ostensibly taking part.