The Greek verb dianoigo means to open completely, to unlock, or to explain thoroughly. The dia prefix intensifies the completeness of the opening. It is used of opening eyes, ears, wombs, scripture, and minds.
Dianoigo is the word used in Luke 24:45 when the risen Christ 'opened their minds so they could understand the Scriptures.' It is also used on the road to Emmaus when Christ 'explained' the Scriptures (v.32). The word captures the essential act of the Holy Spirit — full, complete opening of understanding. Without divine dianoigo, the Scripture remains closed to the natural mind. This is the ministry of illumination.