April 23

And among His signs is the sublimity of His grandeur, His exalted state, His towering glory, and the shining out of His beauty above the horizon of the Prison: so that heads were bowed before Him and voices lowered, and humble were the faces that turned His way. This is a proof never witnessed in the ages gone before.

Again among His signs are the extraordinary things He continually did, the miracles He performed, the wonders appearing from Him without interruption like the streaming down of His clouds—and the acknowledgement, even by unbelievers, of His powerful light. By His own life! This was clearly verified, it was demonstrated to those of every persuasion who came into the presence of the living, the self-subsisting Lord.

And yet another of His signs is the wide-spreading rays of the sun of His era, the rising moon of His times in the heaven of all the ages: His day, which standeth at the summit of all days, for its rank and power, its sciences and its arts, reaching far and wide, that have dazzled the world and astonished the minds of men.

Verily is this a matter settled and established for all time. 
(‘Abdu’l-Baha, ‘Selections from the Writings of ‘Abdu’l-Baha’)