Scientific knowledge is the highest attainment upon the human plane, for science is the discoverer of realities. It is of two kinds: material and spiritual. Material science is the investigation of natural phenomena; divine science is the discovery and realization of spiritual verities. The world of humanity must acquire both. A bird has two wings; it cannot fly with one. Material and spiritual science are the two wings of human uplift and attainment. Both are necessary—one the natural, the other supernatural; one material, the other divine. By the divine we mean the discovery of the mysteries of God, the comprehension of spiritual realities, the wisdom of God, inner significances of the heavenly religions and foundation of the law. (“The Promulgation of Universal Peace”, p. 138) [46] From a Letter Written on Behalf of Shoghi Effendi 47: “Between the truth which comes from God through His Prophets, and the...” Between the truth which comes from God through His Prophets, and the glimmerings, often misunderstood and misinterpreted, of truth which come from the philosophers and thinkers, there is an immense difference. We must never, under any circumstances, confuse the two. Bahá’u’lláh has said that learning can be the veil between the soul of man and the eternal truth; in other words, between man and the knowledge of God. We have seen that many people who become very advanced in the study of modern physical sciences are led to deny God, and to deny His Prophets. That does not mean that God and the Prophets have not existed and do not exist. It only means that knowledge has become a veil between their hearts and the light of God. (22 April 1954 to an individual believer) [47] From Letters Written on Behalf of the Universal House of Justice 48: “Just as there is a fundamental difference between divine Revelation itself...”