Luke 24:45

‘Then opened he their mind, that they might understand the Scriptures.’

This may indicate that, as with the two disciples on the road to Emmaus (see Luke 24:31) He expounded the Scriptures to them, giving them illumination, or it may be a reference to their receiving the Holy Spirit as described in John 20:22, the ‘Spirit of truth’ of John 14-16. or, of course, both. But His basic purpose was to make clear to them the basis of their message, and to recognise how it pointed to Him.