This we are about to undertake in the present treatise. We stand in the Unitarian position, but shall endeavor to see if there be not some truths in Orthodoxy which Unitarians have not yet adequately recognized. To use the language of our motto—we come “not as deserters, but as explorers” into the camp of Orthodoxy. We are satisfied with our Unitarian position, as a stand-point from which to survey that of others. And especially are we grateful to it, since it encourages us by all its traditions, by all its ideas and principles, to look _after_ as well as before—to see if there be no truth behind us which we have dropped in our hasty advance, as well as truth beyond us to which we have not yet attained. § 2. Progress requires that we should look back as well as forward. Such a study as this may be undertaken in the interest of true progress, as well as that of honest inquiry. For what so frequently checks progress, causes its advocates to falter, and produces what we call a reaction towards the old doctrines, as something shallow in the reform itself? Christians have relapsed into Judaism, Protestants into Romanism, Unitarians into Orthodoxy—because something true and good in the old system had dropped out of the new, and attracted the converts back to their old home. All true progress is expressed in the saying of Jesus, “I have not come to destroy, but to fulfil.” The old system cannot pass away until all its truths are _fulfilled_, by being taken up into the new system in a higher form. Judaism will not pass away till it is fulfilled in Christianity—the Roman Catholic Church will not pass away till it is fulfilled in Protestantism—Orthodoxy will not pass away till it is fulfilled by Rational Christianity. Judaism continues as a standing protest, on behalf of the unity of God, against Trinitarianism. And yet we believe that, in the religious progress of the race, Christianity is an advance on Judaism, Protestant Christianity an advance on Roman Catholic Christianity, and Liberal and Rational Christianity an advance on Church Orthodoxy. But all such advances are subject to reaction and relapse. Reaction differs from relapse in this, that it is an oscillation, not a fall. Reaction is the backward swing of the wave, which will presently return, going farther forward than before. Relapse is the fall of the tide, which leaves the ships aground, and the beach uncovered. Reaction is going back to recover some substantial truth, left behind in a too hasty advance. Relapse is falling back into the old forms, an entire apostasy from the higher stand-point to the lower, from want of strength to maintain one’s self in the advance.