Piper exhibits The Probable Trust Registry at the Hamburger Bahnhof, Nationalgalerie Berlin. Completes legal restructuring of APRA Foundation Berlin. Finalizes will. Progressively neglects more and more of yoga practice as deadline pressures for MoMA retrospective increase. Convinces the Berlin city housing construction department to mention some experienced and competent architectural firms able to complete renovation of house. Receives honorary Doctor of Arts from NSCAD University. Honored by Artists Space, New York. Inivited to join National Academy of Art. Signs contract with Central Books Ltd. for distribution of APRA Foundation Berlin print publications. Grieves death at the age of 48, after twelve years of tenure in the Princeton Philosophy Department, of Delia Graff Fara. Grieves death at age 40, after nine years of tenure in the Stanford Mathematics Department, of Maryam Mirzakhani. Discontinues APRA Foundation Berlin Graduate Student Teaching Scholarship in Philosophy at Keele University. Discovers Christopher Dawson's Medieval Essays in parents' library. Exhibits It's Just Art (1980) and Here (2008-2015) at Lévy Gorvy, New York. Writes up "Consistency as Non-Contradiction in Rational Choice Theory." Establishes The Order of Celestial Laughter (2017). Begins work on final chapter of Kant's Metaethics: First Critique Foundations of His Theory of Action. Discovers Johann Huizinga's The Waning of the Middle Ages in parents' library. Sacrifices yoga practice to preparations for MoMA retrospective and publication of Escape to Berlin. Reads Ian Mortimer's The Time Traveler's Guide to Medieval England. Learns Yoga Sutras III.25-IV.1 by heart.