Luke 12:55

When He spoke about preaching, and called it a sword, His hearers may have been troubled, not knowing what He meant. And therefore our Lord adds, that as men determine the state of the weather by certain signs, so ought they to know His coming. And this is what he means by saying, When you see a cloud rise out of the west, straightway you say, There comes a shower. And when you see the south wind blowing, you say, There will be heat, &c. As if He says, Your words and works show me to be opposed to you. You may therefore suppose that I came not to give peace, but the storm and whirlwind. For I am a cloud, and I come out of the west, that is, from human nature; which has been long since clothed with the thick darkness of sin. I came also to send fire, that is, to stir up heat. For I am the strong south wind, opposed to the northern coldness.

Or, they who from the change of the elements can easily when they like predetermine the state of the weather, might if they wished also understand the time of our Lord’s coming from the words of the Prophets.

For the prophets have in many ways foretold the mystery of Christ; it became them therefore, if they were wise, to stretch their prospect beyond to the future, nor will ignorance of the time to come avail them after the present life. For there will be wind and rain, and a future punishment by fire; and this is signified when it is said, A shower comes. It became them also not to be ignorant of the time of salvation, that is, the coming of the Savior, through whom perfect piety entered into the world. And this is meant when it is said, You say that there will be heat. Whence it follows in censure of them, You hypocrites, you can discern the face of the sky and the earth, but how is it that you do not discern this time.

Now we must observe, that conjectures concerning the stars are necessary to the life of man, as long as we do not push our searches into their signs beyond due limits. For it is possible to discover some things with respect to coming rain, still more concerning heat and the force of the winds, whether partial or universal, stormy or gentle. But the great advantage that is rendered to life by these conjectures is known to every one. For it is of importance to the sailor to prognosticate the dangers of storms, to the traveler the changes of the weather, to the husbandmen the abundant supply of his fruits.

But lest any of the people should allege their ignorance of the prophetical books as a reason why they could not discern the courses of the times, He carefully adds, And why even of yourselves judge you not what is right, showing them that although unlearned they might still by their natural ability discern Him, who did works such as none other man did, to be above man, and to be God, and that therefore after the injustice of this world, the just judgment of the creation would come.

But had it not been implanted in our nature to judge what is right, our Lord would never have said this.