From these revelations of the Spirit of God to the saints have proceeded the Scriptures of Truth, which contain:
a. a faithful historical account of the actions of God's people in divers ages, with many singular and remarkable providences attending them;
b. a prophetical account of several things, whereof some are already past, and some are yet to come;
c. a full and ample account of all the chief principles of the doctrine of Christ, held forth in divers precious declarations, exhortations and sentences, which, by the moving of God's Spirit, were at several times and upon sundry occasions spoken and written unto some Churches and their pastors.
Nevertheless, because they are only a declaration of the fountain and not the fountain itself, therefore they are not to be esteemed the principal ground of all truth and knowledge, nor yet the adequate, primary rule of faith and manners. Yet, because they give a true and faithful testimony of the first foundation, they are and may be esteemed a secondary rule, subordinate to the Spirit, from which they have all their excellency and certainty: for as by the inward testimony of the Spirit we do alone truly know them, so they testify that the Spirit is that Guide by which the saints are led into all truth: therefore, according to the Scriptures the Spirit is the first and principal Leader.
Robert Barclay, 1678