O Son of Being! With the hands of power I made thee and with the fingers of strength I created thee; and within thee have I placed the essence of My light. Be thou content with it and seek naught else, for My work is perfect and My command is binding. Question it not, nor have a doubt thereof.(15) The second of the two major works composed by Bahá’u’lláh during this period is The Book of Certitude, a comprehensive exposition of the nature and purpose of religion. In passages that draw not only on the Qur’án, but with equal facility and insight on the Old and New Testaments, the Messengers of God are depicted as agents of a single, unbroken process, the awakening of the human race to its spiritual and moral potentialities. A humanity which has come of age can respond to a directness of teaching that goes beyond the language of parable and allegory; faith is a matter not of blind belief, but of conscious knowledge. Nor is the guidance of an ecclesiastical elite any longer required: the gift of reason confers on each individual in this new age of enlightenment and education the capacity to respond to Divine guidance. The test is that of sincerity: No man shall attain the shores of the ocean of true understanding except he be detached from all that is in heaven and on earth.... The essence of these words is this: they that tread the path of faith, they that thirst for the wine of certitude, must cleanse themselves of all that is earthly--their ears from idle talk, their minds from vain imaginings, their hearts from worldly affections, their eyes from that which perisheth. They should put their trust in God, and, holding fast unto Him, follow in His way. Then will they be made worthy of the effulgent glories of the sun of divine knowledge and understanding, ... inasmuch as man can never hope to attain unto the knowledge of the All-Glorious ... unless and until he ceases to regard the words and deeds of mortal men as a standard for the true understanding and recognition of God and His Prophets. Consider the past. How many, both high and low, have, at all times, yearningly awaited the advent of the Manifestations of God in the sanctified persons of His chosen Ones.... And whensoever the portals of grace did open, and the clouds of divine bounty did rain upon mankind, and the light of the Unseen did shine above the horizon of celestial might, they all denied Him, and turned away from His face--the face of God Himself....