JS wrote a letter from near to on 30 December 1839 in response to one Foster had written six days earlier. JS, who had been with Foster in , had arrived in Philadelphia on 21 December to visit in that city and the surrounding areas. Although and followed JS to Philadelphia two days later, Foster remained in the capital, where he preached and continued to provide medical care for . In his letter, Foster had reported on his recent missionary efforts, including an encounter with an argumentative Methodist clergyman, and had briefly reported on Rigdon’s health. In this reply, JS encouraged Foster in his missionary work and updated Foster on the church’s status in Philadelphia and the Delaware River Valley. JS also reported on the efforts of several apostles and other prominent church leaders who were then preaching in that area prior to departing for to serve a mission.

JS’s original letter is apparently not extant, and it is unknown how JS transmitted it to . No response to the letter has been located. Foster apparently retained possession of this letter until his death in 1878. It was published in the Seattle Daily Chronicle in 1883, prefaced with a statement indicating that an unnamed executor of Foster’s estate lent the letter to a man named John R. Kinnear, who allowed a Daily Chronicle reporter to copy and publish its content. No surviving copies of the issue of the Daily Chronicle that printed the letter have been located. The version featured here is one that the Salt Lake Daily Herald reprinted on 16 November 1883 under the title “Interesting Relic.”