Bahá’í Sacred Writings, Bahá’u’lláh, #61

By My Self! Whoso hath in bygone ages asked Us to produce the signs of God, hath, no sooner had We revealed them to him, repudiated God’s truth. The people, however, have, for the most part, remained heedless. They whose eyes are illumined with the light of understanding will perceive the sweet savours of the All-Merciful, and will embrace His truth. These are they who are truly sincere.