In Sam Shepard's play A Lie of the Mind, humans are revealed as ill-equipped to deal with painful truths. Rather than work to accept them, our minds create alternate realities—lies of the mind—fictions that we can more readily accept and use to explain our pain or misfortune. This is especially true when we are hurt by someone we love and need some way to come to terms with that pain but do not want to accept that it has come at the hands of one for whom we care so deeply. It is for this reason, for example, that Beth creates a fiction in her mind that her family has had her brain removed, as she tells Frankie when she shows him her nonexistent scar. It is easier for her to believe that her family has made her the way she is rather than her husband, who she loves. It is also for this reason that Lorraine creates a fiction in her mind about not caring about her dead, good-for-nothing husband. Though she kept all his belongings and ashes, she claims she only did so for her son Jake. Rather than come to grips with the fact that her husband repeatedly tried to abandon her and their children, it is easier for Lorraine to say that she actually never thought much of him. She even blames her daughter, Sally, for the fact that Jake runs off. Rather than believe the truth that he desperately wanted to escape Lorraine herself, Lorraine tells Sally that "He won't come back now. Thanks to you." It is easier to make it Sally's fault that Jake has escaped rather than admit that she smothered him and that he does not seem to appreciate or love her.

There is a quotation from Cesar Vallejo before the play begins; it reads,

Something identifies you with the one who leaves you, and it is your common power to return: thus your greatest sorrow. Something separates you from the one who remains with you, and it is your common slavery to depart: thus your meagerest rejoicing.

In other words, we become bound to one another when we love, and when the one we love leaves us, we can always go back to them—this is a terrible sorrow as it will likely cause suffering. However, even when we are together with one in love, we are always somehow separated, alienated from them, and so eventually we must leave them; this results in very little happiness. In other words, we seem damned if we stay with the one we love, and we seem damned if we go; either way, we will be unhappy.

The relationships in the text play this idea out. The marriage of Baylor and Meg is unhappy; he is embittered by his life with her, and when he kisses her cheek at the end of the play, she says that he has not kissed her in twenty years. The marriage of Jake and Beth is also unhappy; he beats her so badly that she sustains significant brain damage, and this is, apparently, not the first time he has done so. However, even when she is in the hospital recovering from her injuries, she says of Jake, "HEEZ MY HAAAAAAAAAAART!!!" She continues to love him and even thinks, toward the end of the play, that Frankie is Jake, confusing their voices and bodies. Even the relationships between parents and children are fraught with tension and pain. Ultimately, relationships are our greatest source of pain, yet we cannot resist them.