"It is already...over eight years... I laid aside the gown and surplice" - It is the robes of the clergy. He was an anglican "minister" and also a missionary in the Americas at first.

"Although I enjoyed much pleasant and profitable communion with those among whom I spent seven years abroad" - After leaving the anglican church, he became an assistant pastor in the "Igreja Evangélica Fluminense", a congregational church in Brazil.

Then he found "the brethren" and wrote this letter to his mother.