What follows is my provisional translation (in other words, not official or authorized; see here for more) of a passage from a letter written on behalf of Shoghi Effendi, the original text of which has been published in Má’idiy-i-Ásmání, vol. 3, p. 15. The letter is dated 5 Sulṭán 102 BE (22 January 1946) and was written to a certain “Jináb-i-Qá’im-Maqámí,” possibly Mírzá Áqá Khán Qá’im-Maqámí (1868–1954), a wealthy and eminent Iranian Bahá’í. See here for a biography of Mírzá Áqá Khán Qá’im-Maqámí.
With regard to the philosopher’s stone* [iksír-i-a‘ẓam] and the discovery thereof, the Guardian has instructed me to write, “The practitioners of today’s sciences have yet to unravel its meaning. What has been discovered up to the present time has not had any connection with it.”
==========
* “Philosopher’s stone, in Western alchemy, an unknown substance, also called ‘the tincture’ or ‘the powder,’ sought by alchemists for its supposed ability to transform base metals into precious ones, especially gold and silver. Alchemists also believed that an elixir of life could be derived from it. Inasmuch as alchemy was concerned with the perfection of the human soul, the philosopher’s stone was thought to cure illnesses, prolong life, and bring about spiritual revitalization” (Encyclopedia Britannica).
A typescript of the original Persian text of this passage appears below.