Xiantiandao (先天道), the Way of the Former Heaven, is the name a family of Qing-dynasty sectarian congregations gave to their teaching: the Way that existed before heaven and earth, kept secret through the long ages of the world, and now handed down once, in the last kalpa, to bring the Mother's lost children home. Its patriarchs were counted in a numbered line, and Yiguandao, which spread across China and then the world in the twentieth century, traces its own descent through that line. Its scriptures are the Mother's open letters to her children, revelations brought down by the brush, and older precious scrolls reissued under its patriarchs' names.

The room opens with The Family Letter from the Jade Pool, a revealed letter of the winter of 1874–75 in which the Mother of the Infinite weeps for her children, warns of the last kalpa, and names the One Thread as the secret of the Way. It is translated in full from the Chinese of a woodblock recut in 1918, with the complete source text beneath the English.