John Calvin Commentary John 4:35

"Say not ye, There are yet four months, and [then] cometh the harvest? behold, I say unto you, Lift up your eyes, and look on the fields, that they are white already unto harvest." — John 4:35 (ASV)

Do you not say? He develops the preceding statement; for, having said that nothing was more dear to him than to finish the work of the Father, he now shows how ripe it is for execution; and he does so by a comparison with the harvest. When the corn is ripe, the harvest cannot bear delay, for otherwise the grain would fall to the ground and be lost; and, in like manner, the spiritual corn being now ripe, he declares that there must be no delay, because delay is injurious.

We see for what purpose the comparison is employed; it is to explain the reason why he hastens to perform his work. By this expression, Do you not say? he intended indirectly to point out how much more attentive the minds of people are to earthly than to heavenly things. For they burn with so intense a desire for harvest that they carefully count up months and days, but it is astonishing how drowsy and indolent they are in gathering the heavenly wheat.

And daily experience proves that this wickedness not only is natural to us, but can scarcely be torn from our hearts; for while all provide for the earthly life to a distant period, how indolent are we in thinking about heavenly things? Thus Christ says on another occasion, Hypocrites, you discern by the face of the sky what sort of day tomorrow will be, but you do not acknowledge the time of my visitation (Matthew 16:3).