1887 - Baha'u'llah uses the term Hand of the Cause for the first time
Towards the end of His life He revealed a Tablet to each one of these souls, designating them as 'Hands of the Cause of God'. As far as we can gather, the first time He used the term 'Hand of the Cause' to refer to an individual with certain responsibilities was in a Tablet revealed in honour of Ibn-i-Asdaq on 19 Rajab 1304 (13 April 1887). Perhaps all three Hands of the Cause were appointed around the same time.
(Adib Taherzadeh, The Revelation of Baha'u'llah v 4, p. 277)
13 April 1912 Talk at Home of Mr. and Mrs. Alexander Morten 141 East Twenty-first Street, New York
1912 - Juliet Thompson meets Abdul-Baha
It was on Saturday, 13 April, that Mamma and I visited the Master. On Friday He had called me early, asking me to meet Him at the MacNutts'.
I shall never cease to see Him as He looked speaking from their stairway, standing below a stained glass window in a ray of sunlight, the powerful head, the figure in its flowing robes, outlined in light. The Master has a strange quality of beautifying His environment, of throwing a glamour over it and blotting out the ugly. The MacNutts' house is ugly; the one redeeming feature of that stairway, its window. All I saw as the Master stood there was Himself, the window, the ray of light. His words lifted my soul on wings! (Diary of Juliet Thompson)
1919 - The Passing of Phoebe Hearst
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