This is one of many echoes of Tennyson's poem The Lady of Shalott (1833). The famous ballad tells of a beautiful damsel cloistered on the island of Shalott, where "she weaves by night and day / A magic web with colours gay", an activity paralleled by the governess's habitual knitting and sewing. The Lady sees the world only through a magic mirror; if she should ever look away from it and into the real world it reflects, an ancient curse will be unleashed upon her. In essence, Tennyson is describing the experience of the artist/writer, whose obligation to create a shadowy duplicate of the real world prevents her from directly experiencing it. The Lady violates these proscriptions when she looks out of the window at Sir Lancelot.
Out flew the web and floated wide;
The mirror crack'd from side to side;
"The curse is come upon me," cried
The Lady of Shalott.
Not only does the governess in The Turn of the Screw share much of the Lady's role, at this moment she also partakes of something of her fate. If, as the reader by now strongly suspects, the governess has been weaving a narrative from the stuff of fantasy, we now see her fulfilling a desire to enter into the real world. When she finally speaks the name of Miss Jessel aloud, the collision of the imaginary and the objective results in a crisis of destruction. Just as the cracking of the glass and the vanishing of the weaving represent the annihilation of the Lady's creative constructions in Tennyson's poem, the shattering effect of the governess's words signals the collapse of the fiction which she has built up around the children, perhaps with their collusion.