In this world we judge a cause or movement by its progress and development. Some movements appear, manifest a brief period of activity, then discontinue. Others show forth a greater measure of growth and strength, but before attaining mature development, weaken, disintegrate and are lost in oblivion. Neither of these mentioned are progressive and permanent.
There is still another kind of movement or cause which from a very small, inconspicuous beginning goes forward with sure and steady progress, gradually broadening and widening until it has assumed universal dimensions. The Bahá'í Movement is of this nature. For instance, when Bahá'u'lláh was exiled from Persia with 'Abdu'l-Bahá and the rest of His family, they traveled the long road from Tihran to Baghdad, passing through many towns and villages. During the whole of that journey and distance they did not meet a single believer in the Cause for which they had been banished. At that time very little was known about it in any part of the world. Even in Baghdad there was but one believer who had been taught by Bahá'u'lláh Himself in Persia. Later on, two or three others appeared. You will see, therefore, that at the beginning the Cause of Bahá'u'lláh was almost unknown, but on account of being a divine Movement it grew and developed with irresistible spiritual power until in this day, wherever you travel -- East or West -- and in whatever country you journey, you will meet Bahá'í assemblies and institutions. This is an evidence that the Bahá'ís are spreading the blessings of unity and progressive development throughout the world under the direction of divine guidance and purpose, while other movements which are only temporary in their activities and accomplishments have no real, universal significance. (Abdu'l-Baha, The Promulgation of Universal Peace, p. 44)