I would therefore entreat the people of God to be very cautious how they give heed to [seeking experience]. I have seen them fail in very many instances. I know by experience that impressions being made with great power, and upon the minds of true, yea eminent,—saints even in the midst of extraordinary exercises of grace, and sweet communion with God, and attended with texts of Scripture strongly impressed on the mind—are no sure signs of their being revelations from heaven.