The prophet Haggai in speaking of God’s blessing on the harvest which was to come said, “Consider now from this day and upward, from the four and twentieth day of the ninth month, even from the day that the foundation of the LORD’s temple was laid, consider it. Is the seed yet in the barn? Yea, as yet the vine, and the fig tree, and the pomegranate, and the olive tree, hath not brought forth: from this day will I bless you.” (Haggai 2:18-9)
“The ‘seed’ refers not to what had been gathered, but to what had been sown. The prophet speaks of God’s blessing on the harvest which was to come. As they were still in suspense, he says that God’s blessing was in readiness for them. The truth of the prophecy might be truly known when God fulfilled what he had spoken by the mouth of his servant. It was necessary for him to speak in a manner suitable to the comprehension of the people, as a skillful teacher who instructs children and those of a riper age in a different manner. The prophet dwells on two things: 1) he condemns the Jews for their neglect, and 2) proves that they were impious and ungrateful toward God, for they disregarded the building of the temple, and then in order to animate them and render them more active in the work they had begun, he sets before them what had taken place.”
By John Calvin, Devotions and Prayers by John Calvin, Still Waters Revival Books, p. 89.