“Phasmes” and “Hêtre,” two signature works of Companie Libertivore, at PS21, December 21–22, 7 pm. Written and choreographed by Fanny Soriano with her trademark merging of dance and acrobatics, Phasmes (2017) is a duet that explores the intimate encounter between human beings and the natural world. It is a companion piece to the earlier Hêtre (2015), a solo work that dramatizes a young woman’s retreat from the world into a mysterious, dreamlike forest. Together they form a diptych, displays of aerial and earthbound movement both delicate and poetic, acrobatic and muscular. A meeting of dance and circus arts, the works induce a slow metamorphosis of humans and organic matter, as performers confront nature, accompany it, dodge it, collide, and merge with it.