The endowments which distinguish the human race from all other forms of life are summed up in what is known as the human spirit; the mind is its essential quality. These endowments have enabled humanity to build civilizations and to prosper materially. But such accomplishments alone have never satisfied the human spirit, whose mysterious nature inclines it towards transcendence, a reaching towards an invisible realm, towards the ultimate reality, that unknowable essence of essences called God. The religions brought to mankind by a succession of spiritual luminaries have been the primary link between humanity and that ultimate reality, and have galvanized and refined mankind's capacity to achieve spiritual success together with social progress.