Michael Arthur was a minister in the Anti-Burgher branch of the Secession Church during the latter half of the eighteenth century. In the course of his ministry he delivered lectures on the Westminster Shorter Catechism, which he later published in three volumes. This work is extracted from the first volume and consists of his exposition of Question Twenty, concerning the covenant of grace. The original spelling has been retained, with only minor editorial adjustments made to matters of layout and presentation. As a minister in the Secession Church, Arthur taught within a stream of covenant theology that sought to preserve and clarify the classic Reformed distinction between law and gospel. Following the theological trajectory represented by Thomas Boston and others associated with the Marrow tradition, the Seceders emphasized a bicovenantal framework and the freeness of the covenant of grace, particularly by underscoring its unconditional nature as fulfilled in Christ and the testamentary manner in which its benefits are offered in the gospel to all men without exception. Out of print since its initial publication, this work is now made available with the hope that it may serve as a valuable introduction to the warmly evangelical federal theology of the Seceders, and with the prayer that it may prove a timely and salutary corrective to the reappearance of Baxterian tendencies, by which the gospel is obscured through the imposition of conditions upon grace and the confusion of law and gospel, to the great detriment of the Kirk in our day.