Very fine and extensive 4pp 1829 letter [ALS] from a young Thomas Brainerd, addressed to Wait Talcott, the abolitionist politician and an early friend and supporter of Thomas on his way into the Christian Ministry. Talcott was also friends with Charles G. Finney and they worked together on the issue of abolition in the Midwest.

Extracts:

Dearly beloved friend, Protected by that unseen yet kind hand which sustains the universe I arrived at this place in health on the 13th inst and am again permitted to enjoy the agreeable society of my endeared Christian brethren in this school of the people. 

I was much delighted to find Francis in the city of New York... and turning my eyes to the city & its hundred steeples glittering in the sun... grew dim in the distance ... I felt a melancholy pang to observe the rapidity with which the almost flying vessel was bearing me from that I loved and by whom I am loved.

He thanks Talcott for the Oneida Republican and "for the many instances of kindness and affection you manifested me during my last visit ... I am certain that Mr. Finney (Rev. Charles G. Finney) has lately gone to the West, he may be in Rome, if so I shall glad to hear what is the result of his labours. I hope we shall both awake to a greater sense of our responsibility as Christians and strive to do from day to day every duty incumbent upon us.

BIOGRAPHY:

Thomas could not have wished for a godlier ancestry. Born in 1804, he was a part of one of the most notable, pious families in America; his relatives including the sainted David Brainerd, friend and biographee of Jonathan Edwards and missionary to the Susquehanna Indians. Of John Brainerd, who took up after David, his brother, and served for 34 years as missionary to the Native Americans. Thomas would later write his biography.

Yet the young Thomas remained unconverted, unChristian until he met and heard the radical, Charles G. Finney 1825. The experience shook him and he became a Christian. Finney became something of a mentor to the young Brainerd, and probably took a special delight knowing his family history. The young Brainerd and Charles G. Finney enjoyed a regular correspondence, much of which was later reprinted in the Oberlin Evangelist.

After a time as an itinerant and then pastor in Cincinnati, where he befriended another revivalist, Lyman Beecher, he was installed as pastor of Third (Old Pine) Presbyterian Church, Philadelphia, where he served for 30 years, until his death in 1866. 

See here for examples of their correspondence: 

http://gospeltruth.net/Finneyletters/finlets/finlet%201821-1829%20done/finlet1828-10_21.htm

By 1856, they were still in correspondence. See here:

https://www.charlesgfinney.com/Finneyletters/finlets/finlet%201855-1859/finlet1856-02_12.htm

The full biography of Thomas Brainerd, published 1870, is available here: 

https://books.google.com/books?id=08gf7LYEvYMC&pg=PA55&lpg=PA55&dq=%22wait+talcott%22+finney&source=bl&ots=u2o3VtJ7KT&sig=ACfU3U0KmrG5wpEyNawRdejyoSRyDZedig&hl=en&sa=X&ved=2ahUKEwjY0_PbuLTtAhXZVs0KHb4wAA0Q6AEwAXoECAEQAg#v=onepage&q=%22wait%20talcott%22%20finney&f=false