Whenever a certain flicker — of curiosity, recognition and bone-deep affinity — lights up the gaze of the woman who calls herself Sugar, brace yourself for a good (and good is the word) cry. You can first spot that wakening flame in the opening minutes of “Tiny Beautiful Things,” the handkerchief-soaking meditation on pain, loss, hope and forgiveness that opened on Wednesday night at the Public Theater.

At that point, a professional writer who is also a mother of two has just agreed, via phone, to be the agony aunt for an unpaid online advice column called “Dear Sugar.” Portrayed by Nia Vardalos, the newly anointed Sugar finds her toy-cluttered kitchen and living room invaded by a multitude of voices, embodied by three performers who circle her like wandering satellites.

Questions pour out of them, about being seasick and about being spied on (by the widow next door), about needing money and about having an eighth-grade science class partner who picks his nose. But it’s the guy who identifies himself as “Confused” who causes Sugar to open her eyes wider and really, really focus.

What confuses “Confused” is love. And love is a topic on which Sugar has definite and profound opinions. She starts to talk, gropingly at first. But then she lands on the subject of her last encounter with her dying mother, many years earlier. And you suddenly find yourself in the midst of what feels like a delicately wrought chapter in a memoir — except, somehow, this memoir is as much about you as it is about its author.