2 Kings 19:29

And this shall be a sign unto thee, Ye shall eat this year such things as grow of themselves, and in the second year that which springeth of the same; and in the third year sow ye, and reap, and plant vineyards, and eat the fruits thereof.

This shall be a sign unto thee, Ye shall eat this year such things as grow of themselves ... The "sign" which Isaiah goes on to promise, in terms apparently made obscure in order to excite consideration, seems best explained to mean, that the Assyrian devastations of the open country of the Jews had prevented the regular cropping of the land, and consequently the regular harvest for the current year; and as the enemy was still in occupation of the country, there was no possibility of plowing and sowing, in preparation for the next year either; but the season after that, the prophet confidently asserts that they would be able to sow and reap, and plant vineyards, and eat the fruit thereof.

The promise is thus brought into strict harmony with the previous threat (cf. Isaiah 32:10), that 'the vintage should fail, and the gathering not come' for a time, which we must understand Isaiah thereby to say would be considerable; whether we understand the 'days above a year,' of the original, to mean 'more than full year,' or look only at the general expressions in the following verses of the passage referred to. That what Isaiah said there, he may have meant here, might seem answer enough to the objection, that those who give this explanation of the loss of two harvests, must suppose the prophet to have expected the Assyrian occupation to last much longer than the history shows that it did; but the objection itself vanishes, if we recollect that the movements of great armies against and over a country defended by deserts and mountains and fortified cities, the political negotiations preceding and following these movements, and the recovery of depopulated villages and wasted grain-fields and vineyards, were not events which could begin and end within any such short space as it takes to write or read of them.

'This sign is analogous in character to all other symbols (cf. Genesis 9:1; Exodus 3:12; Isaiah 7:14; Isaiah 8:1) of which the purpose is, not to establish faith in a future miracle, because a present one has been performed, but to supply such an outward and visible sign of the accompanying inward spiritual grace as will, from the very constitution of man's being, help him to realize the latter, as he could not do by any naked mental effort. And the thing here signified has itself an inward and an outward part; for as the spontaneously-sowed and multiplied grain and fruit will be the foundation and materials of the regular cultivation of the third year, so will the deserted villages and farms be replenished with the survivors of those who have for the present found refuge within the walls of Jerusalem; and both the one and the other will be the types of "holy seed," the existence of which in the corrupt nation was made know to Isaiah at his first calling to the prophetic office, when he was told that he was to watch and wait with the long patience of the farmer for the growing up of that seed, after the hard ground had been broken up, and the rampant weeds rooted out, by the plowshare of repeated national calamities' (Strachey, 'Hebrew Politics,' p. 280).