For man two wings are necessary. One wing is physical power and material civilization; the other is spiritual power and divine civilization. With one wing only, flight is impossible. Two wings are essential. Therefore, no matter how much material civilization advances, it cannot attain to perfection except through the uplift of spiritual civilization. All the Prophets have come to promote divine bestowals, to found the spiritual civilization and teach the principles of morality. Therefore, we must strive with all our powers so that spiritual influences may gain the victory. For material forces have attacked mankind. The world of humanity is submerged in a sea of materialism. The rays of the Sun of Reality are seen but dimly and darkly through opaque glasses. The penetrative power of the divine bounty is not fully manifest. ‘Abdu’l‑Bahá, The Promulgation of Universal Peace. Available from www.bahai.org/r/202957535