John Calvin Commentary Luke 18:34

"And they understood none of these things; and this saying was hid from them, and they perceived not the things that were said." — Luke 18:34 (ASV)

And they understood none of these things. What stupidity was this, not to understand what Christ said to them in a plain and familiar manner, on a subject not too lofty or intricate, but about which they had, at their own suggestion, entertained some suspicion!

But it is also proper to bear in mind—as I have formerly observed—the reason why they were held in such gross ignorance, which was that they had formed the expectation of a joyful and prosperous advancement and therefore considered it to be in the highest degree absurd that Christ should be ignominiously crucified.

From this we infer with what madness the minds of men are seized by a false imagination; and therefore we ought to be the more careful not to yield to any foolish thoughts and shut our eyes against the light.