In the early days of the Faith in Isfahan, when I began to study the Tablets and Writings of the Báb, and listen to the explanations of the friends, I found the proofs of His Revelation convincing and conclusive and the testimonies supremely sound and perfect. So I was assured in myself that this Cause was the Cause of God and the Manifestation of His Grandeur, the dawning of the Day-Star of Truth promised to be revealed by the Almighty. But when I was alone with no one to talk to, I was often overtaken with doubts. The idle fancies of my past life, and the whisperings of the evil one were tempting me... God knows how much I wept and how many nights I stayed awake till morning. There were days when I forgot to eat because I was so immersed in my thoughts. I tried by every means to relieve myself of these doubts. Several times I became steadfast in the Cause and believed, but later I would waver and become perplexed and dismayed.
(Adib Taherzadeh, Revelation of Bahá’u’lláh, v2, p. 197)