NYFW Spring/Summer 2021 – Theory September 17, 2020 New York Fashion Week Spring/Summer 2021: Theory. For this NYFW S/S 2021, Theory explores a changing world through reinvention and renewal. New York Fashion Week Spring/Summer 2021: Theory. Images courtesy of Theory. GUILD MAGAZINE - THE FASHION ISSUE We are glad you are enjoying our articles! To read more content from our fashion issue, order your copy below. Thank you for being a loyal reader of Guild Magazine! ORDER NOW Share this article: