John Calvin Commentary Luke 24:45

"Then opened he their mind, that they might understand the scriptures;" — Luke 24:45 (ASV)

Then He opened their understanding. As the Lord had formerly carried out the role of Teacher, with little or no improvement from the disciples, He now begins to teach them inwardly by His Spirit. For words are coldly wasted on the air until their minds are enlightened by the gift of understanding. It is true, indeed, that

the word of God is like a lamp,
(Psalms 119:105)

but it shines in darkness and among the blind until the inward light is given by the Lord, to whom it uniquely belongs to enlighten the blind, (Psalms 146:8). Thus it is evident how great is the corruption of our nature, since the light of life presented to us in the heavenly oracles is of no use to us.

Now if we do not perceive by the understanding what is right, how would the will be sufficient for yielding obedience? We ought, therefore, to acknowledge that we fall short in every respect, so that the heavenly doctrine becomes useful and effective to us only insofar as the Spirit both forms our minds to understand it and our hearts to submit to its yoke.

Therefore, to be properly qualified to become His disciples, we must set aside all confidence in our own abilities, seek light from heaven, and, abandoning the foolish opinion of free will, surrender ourselves to be governed by God. Nor is it without reason that Paul instructs people

become fools, that they may be wise to God,
(1 Corinthians 3:18)

For no darkness is more dangerous to quench the light of the Spirit than reliance on our own discernment.

That they might understand the Scriptures. Let the reader next observe that the disciples did not have the eyes of their minds opened so as to comprehend the mysteries of God without any help, but only insofar as they are contained in the Scriptures; and thus was fulfilled what is said:

(Psalms 119:18) Enlighten mine eyes,
that I may behold the wonders of thy law.

For God does not grant the Spirit to His people in order to set aside the use of His word, but rather to render it fruitful. It is highly improper, therefore, for fanatics, under the pretense of revelations, to take the liberty of despising the Scriptures. For what we now read concerning the apostles is daily accomplished by Christ in all His people: namely, that by His Spirit He guides us to understand the Scriptures, and does not carry us away into the idle raptures of enthusiasm.

But it may be asked: Why did Christ choose to waste His labor during the entire period of three years in teaching them, rather than to open their understandings from the very beginning?

I reply, first, though the fruit of His labor did not immediately appear, it was still not useless. For when the new light was given to them, they also perceived the benefit of the former period.

For I regard these words as meaning not only that He opened their understandings, so that in the future they might be ready to receive instruction if anything was said to them, but also that they might recall His doctrine, which they had previously heard without any benefit.

Next, let us learn that this ignorance, which lasted for three years, was very useful in showing them that they obtained their new discernment from no other source than from the heavenly light.

Besides, by this fact Christ gave an undoubted proof of His divinity. For He not only was the minister of the external voice, which sounded in their ears, but by His hidden power He penetrated their minds. Thus He showed that what Paul (1 Corinthians 3:7) says does not belong to the teachers of the Church is the prerogative of Him alone.

Yet it should be observed that the apostles were not so lacking the light of understanding that they did not hold certain elementary principles. But since it was only a slight taste, it is considered to be a beginning of true understanding when the veil is removed, and they behold Christ in the Law and the Prophets.