The resistless march of the Faith of Bahá'u'lláh,

"From the record of its tumultuous history, almost every page of which portrays a fresh crisis, is laden with the description of a new calamity, recounts the tale of a base betrayal, and is stained with the account of unspeakable atrocities, there emerges, clear and incontrovertible, the supreme truth that with every fresh outbreak of hostility to the Faith, whether from within or from without, a corresponding measure of outpouring grace, sustaining its defenders and confounding its adversaries, has been providentially released, communicating a fresh impulse to the onward march of the Faith, while this impetus, in its turn, would through its manifestations, provoke fresh hostility in quarters heretofore unaware of its challenging implications--this increased hostility being accompanied by a still more arresting revelation of Divine Power and a more abundant effusion of celestial grace, which, by enabling the upholders of that Faith to register still more brilliant victories, would thereby generate issues of still more vital import and raise up still more formidable enemies against a Cause that cannot but, in the end, resolve those issues and crush the resistance of those enemies, through a still more glorious unfoldment of its inherent power.
 The resistless march of the Faith of Bahá'u'lláh, viewed in this light, and propelled by the stimulating influences which the unwisdom of its enemies and the force latent within itself, both engender, resolves itself into a series of rhythmic pulsations, precipitated, on the one hand, through the explosive outbursts of its foes, and the vibrations of Divine Power, on the other, which speed it, with ever-increasing momentum, along that predestined course traced for it by the Hand of the Almighty."

(Hand-written postscript 12 August 1941, Shoghi Effendi: Messages to America: Selected Letters and Cablegrams Addressed to the Bahá'ís of North America, 1932-1946. Bahá'í Publishing Trust, Wilmette, 1947. p. 51)