Q. Who shall have the power of interpreting scriptures?
The Papists do assert that it is in the power of the church. If you ask who they mean by the church, they say, the Pope who is head of it, and he is infallible; so Bellarmine. But that assertion is false, because many of the Popes have been ignorant and vicious, as Platina affirms, who writes of the lives of Popes. Pope Liberius was an Arian; and Pope John XII. denied the immortality of the soul; therefore Popes are not fit interpreters of scripture. Who then?
A. The scripture is to be its own interpreter, or rather the Spirit speaking in it; nothing can cut the diamond but the diamond; nothing can interpret scripture but scripture; the sun best discovers itself by its own beams; the scripture interprets itself in easy places to the understanding. But the question is concerning hard places of scripture where the weak Christian is ready to wade beyond his depth. Who shall interpret here?
A. In the church, God hath appointed some to expound and interpret scripture; therefore he hath given gifts to men; the several pastors of churches, like bright constellations, give light to dark scriptures: Mal. 2:7., “The priest’s lips should keep knowledge, and they should seek the law at his mouth.”

Watson, T. (1855). The Select Works of the Rev. Thomas Watson, Comprising His Celebrated Body of Divinity, in a Series of Lectures on the Shorter Catechism, and Various Sermons and Treatises (p. 25). Robert Carter & Brothers.