John Calvin Commentary Luke 24:38

"And he said unto them, Why are ye troubled? and wherefore do questionings arise in your heart?" — Luke 24:38 (ASV)

Why are you troubled? By these words they are urged to lay aside terror and regain possession of their minds, so that, having returned to the clarity of their senses, they may judge a matter which is fully confirmed. For as long as people are seized with agitation, they are blind amidst the clearest light. Therefore, in order that the disciples may obtain certain information, they are instructed to weigh the matter with calmness and composure.

And why do thoughts arise in your hearts? In this second clause, Christ rebukes another fault: that by the variety of their thoughts they create difficulties for themselves. By saying that thoughts arise, He means that the knowledge of the truth is choked in them, so that seeing they do not see (Matthew 13:14). For they do not restrain their wicked imaginations; on the contrary, by giving them free rein, they allow them to prevail.

And we certainly find it true that, just as when the sky has been clear in the morning, clouds afterward arise to darken the clear light of the sun, so when we allow our reasonings to arise with excessive freedom in opposition to the word of God, what previously appeared clear to us is withdrawn from our eyes.

We do indeed have a right, when any appearance of absurdity presents itself, to inquire by weighing the arguments on both sides. And indeed, as long as matters are doubtful, our minds must inevitably be driven about in every direction. But we must observe sobriety and moderation, lest the flesh exalt itself more than it should and cast its thoughts far and wide against heaven.