Teilhard's work as a paleontologist confirmed his commitment as priest and scientist. He saw the human species as the leading shoot of evolution, and suggested that it is increasingly capable of influencing, for good or ill, the future course of planetary and cosmic evolution. His works construct a synthesis of mysticism, spirit, science and faith. His seminal contribution to twentieth-century thought was recognized by the world community at the UNESCO symposium held in his honor in Paris in 1981. In 1981 and again in 1995 the Catholic Church and the Society of Jesus recognized the major contribution he had made to Christian thought. The Teilhard Lexicon has been written to enable researchers and students to better understand the specialized language of Teilhard's transdisciplinary approach. He found himself compelled to develop this approach as a means of expressing that extraordinary vision of a universe in process of convergence towards a cosmic center of unity he identifies with the Cosmic Christ. The Lexicon is based on, but surpasses in terms of length and breadth, the Nouveau lexique Teilhard de Chardin by Claude Cuénot (1968). All quotations in the Lexicon have been sourced from the French originals. The Lexicon is essential reading for all those who wish to come to grips with the language Teilhard used to bring together evolutionary cosmology and Christian theology.