I have come to your city and found tall buildings and advancement in material civilization. Now I will lead you to my own city which is the world above. Its administration is the oneness of humanity, its law is international peace, its palaces are ever shining with the lights of the Kingdom, its season is always spring, its trees are ever green, its fruits are fresh and sweet, its sun is ever ascending, its moon is always full, its stars are ever brilliant and its planets are ever circling. That is our city and the Founder is Bahá'u'lláh. We have enjoyed the pleasures of this city and now I invite you to that city. I hope that you will accept this invitation.
- 'Abdu'l-Baha (Words of ‘Abdu’l-Baha, 25 September 1912, Denver, Colorado, USA, recorded by Mahmud Zarqani; ‘Mahmud’s Diary’)