This is an unedited reprint of a collection of tracts about the doctrine of the Trinity published by Thomas Firmin (1632-97) in 1691. It was a major shot in a war of words among Anglicans about the doctrine of the Trinity from about 1687-98. (For an overview of this, see Dixon's Nice and Hot Disputes.)

The first part contains some writings from Firmin's long-departed friend John Bidle (Biddle) (1615-62) - the first prominent English unitarian.

The second contains seven controversial, anonymous writings, about half of which are thought to be by Firmin's friend, the Reverend Stephen Nye (1648-1719). Some central points: the traditional, Athansian doctrine of the Trinity is inconsistent with itself, and with the Bible. Further, several then-recent traditionalist attempts to spell out what the Trinity doctrine amounts to are criticized.

These tracts include the second, revised edition of A Brief History of the Unitarians, Called also Socinians. In Four Letters to a Friend.