This is a collection of lectures delivered as part of the commemoration of the hundredth anniversary of the writing of The Mass on the World , October 16-22, 2023 by Teilhard-Monde and the Association des Amis de Pierre Teilhard de Chardin, in partnership with the American Teilhard Association. This event took place in New York, the city that hosted Teilhard during the last years of his life, and in Hyde Park NY, where he is buried. Throughout the week-long celebration, presentations by Teilhard’s relatives and Teilhard scholars from around the world and a walking tour in Teilhard's footsteps in Manhattan brought to life Teilhard’s impassioned thought addressed to the soul of a world in upheaval and informed by his vision of a world still in the making.