Webster: the clarity of Holy Scripture

Scripture is self-interpreting and perspicuous by virtue of its relation to God ... The clarity of Scripture is a function of its place in the divine self-demonstration, and of the Spirit’s work of ordering the mind, will and affections of the reader towards what Calvin called ‘heavenly doctrine’. Perspicuity only makes sense when seen in a soteriological context, that is, in relation to God’s act as Word and Spirit and the creature’s act of faith. Like other properties of Scripture, such as sufficiency, efficacy or perfection, clarity is not a formal or natural property of the text considered in isolation. ... Rather, Scripture is clear because through the Spirit the text serves God’s self-presentation. Properly speaking, it is not Scripture which is self-interpreting but God who as Word interprets himself through the Spirit’s work. ... Scripture is clear because of the Spirit’s work in which creaturely acts of reading are so ordered towards faithful attention to the divine Word that through Scripture the light of the gospel shines in its own inherent splendour. Perspicuity is thus not a way of suggesting that reading is superfluous; it is about the way in which faithful reading within the economy of revelatory grace is not sheerly spontaneous but a receptive act of the intelligence of faith. ... In sum: Scripture’s clarity is neither an intrinsic element of the text as text nor simply a fruit of exegetical labour; it is that which the text becomes as it functions in the Spirit-governed encounter between the self-presenting saviour and the faithful reader. To read is to be caught up by the truth-bestowing Spirit of God.
—John Webster, Holy Scripture: A Dogmatic Sketch (Cambridge: Cambridge UP, 2003), 93-95.