The illumination of the Holy Spirit is "[t]he process by which God's Holy Spirit enables us to understand His word and apply it to our lives." 
"The Reformers, and particularly John Calvin, stressed the way the objective, written Word and the inner, supernatural ministry of the Holy Spirit work together, the Holy Spirit illuminating the Word to God's people. The Word without the illumination of the Holy Spirit remains a closed book." - James M Boice
It is "not a giving of new revelation, but a work within us that enables us to grasp and to love the revelation that is there before us in the biblical text as heard and read, and as explained by teachers and writers."^^
The necessity of the illumination of the Holy Spirit does not negate the doctrine of the clarity of Scripture.
- John Owen's View of Illumination: An Alternative to the Fuller-Erickson Dialogue (PDF), by David J. McKinley
- The Holy Spirit and Hermeneutics, by Daniel B. Wallace
- Illumination - The Holy Spirit Gives Spiritual Understanding, by J.I. Packer
- The Illumination of the Holy Spirit, by Bernie Gillespie
- The Holy Spirit's Role in Biblical Interpretation, by Daniel P. Fuller - "This refusal to welcome the teachings of the Bible hardly excludes, however, the natural man's having a cognition of what he repudiates. To the contrary, the fact that he experiences a revulsion against a biblical teaching presupposes a prior cognition of that teaching, for how can a man hate something without having some knowledge of it? ... Even though the teachings of the Bible are manifestly reasonable, our reasoning powers are not sufficient to suppress the awesome power of sin which predisposes us to glory in ourselves. Only God, through the Holy Spirit, overcomes this power of sin, so that we are willing to love from the heart what our minds can tell us is reasonable."
- The Holy Spirit's Illumination of Scripture, by Alwyn York
- The Holy Spirit In the Ministry of the Word, by Bob Burridge
- Reason, Sin and Illumination, by John Calvin - From The Institutes of the Christian Religion
- Open My Eyes That I May See, by John Piper
- The Holy Spirit “Illumination” Theory: A Critical Review, by Wayne Jackson - "The doctrine of special illumination contradicts the clear testimony of Scripture, namely the explicit affirmation that the devout student is able to understand the Word of God as given originally."