Amy Kirby (later Amy Kirby Post) was the daughter of Jacob and Mary Seaman Kirby, who lived in Locust Grove, on Long Island. The family were longtime Quakers, and members of Jericho Monthly Meeting, well-known as the meeting of Elias Hicks (1748-1830). In 1827-1828 the Society of Friends would undergo their most severe schism, as the reformers, dubbed Hicksites after one of their leading spirits, split off from the Orthodox Friends. In Hicks' own monthly meeting, all but twelve of the 199 members would join the Hicksites. Amy referred to the much older Hicks as her "cousin," and like many of the Jericho Friends, they were related by marriage, if not by blood.
In 1824, Amy Kirby and her family traveled three hundred miles west to Skaneateles, in Onondaga County, New York. It is possible that they were visiting Amy's sister Hannah, who had married Isaac Post at Jericho MM in 1821, and removed to Skaneateles, where they were probably members of Scipio Monthly Meeting. While visiting, Amy either met or revived an acquaintance with Charles Willets, a Quaker man who had most likely been a member of Jericho before removing to the finger lakes region. He was probably the son of William Willets and his first wife, Latitita Valentine, members of Westbury MM, the meeting Jericho was set off from in 1789.
Upon her return home, Amy received a letter from Charles, in which he professed his love for her. This was the beginning of a candid epistolary courtship. Occasionally Amy addressed her letters to Isaac Post rather than Charles, in what was probably a feeble attempt to put the watchful townspeople off the scent of her blooming romance. Sadly, Charles Willets died in late May or early June of 1825, leaving Amy desolate. By 1828 she had recovered sufficiently to marry Isaac Post, her former brother-in-law. Her older sister Hannah had died, leaving at least one motherless child, for a daughter Mary had been born in 1823. Amy and Isaac Post either withdrew or were disowned from the Society of Friends in the mid-1840s. Radical reformers, they were active in the abolitionist movement, woman suffrage, and other burning issues of the day. The Posts were two of the first promoters and protectors of the controversial spiritualists, the Fox sisters. In 1852, Isaac, acting as a "writing medium," published Voices from the Spirit World, which included messages from George Fox and Elias Hicks.