In Lauren Gunderson’s clever and charming 2008 play, we meet Emilie, Voltaire’s erudite mistress, in a foggy, existential spotlight that she investigates—testing its boundaries and groping at its solidity (wave, particle, what?)—while discussing her earthly existence. This bifurcated prelude sets the tone for the piece, in which now-dead Emilie (the intense and compelling Kate Witt) compares relative merits of love and philosophy by tallying them on a chalkboard. Her lessons are tableaux vivants featuring a small but dexterous ensemble. Star of many of these scenes is powdery wag Voltaire, called “V” for short (a perfectly cast Nick DeSantis), whose poisonous relationship with the married Emilie is hilarious, believable, and infuriating. Because Emilie’s world is so split between reason and passion, her emotional, feminine self is portrayed by a second actress, the daintier Sara Coates. And in some of the play’s most effective scenes, the two Emilies meet, expressing both jealousy and the desire to unite. MARGARET FRIEDMAN (See Margaret’s full review.)

Wednesdays-Saturdays, 7:30 p.m.; Sundays, 3 p.m. Starts: Jan. 26. Continues through Feb. 20, 2011