So urgent was the message he had to deliver, that (according to one Evangelist) a man who wished to bury his father before joining him was told to let the dead bury their dead, but to go himself and announce the kingdom of God; while another, who asked leave to bid farewell to his family, was warned that no man, having put his hand to the plough, and looking back, was fit for that kingdom (Lu. ix. 58-62). The arrival of the kingdom was to be preceded by various signs. There would be false Christs; there would be wars, earthquakes, and famines; there would be persecutions of the faithful; but the Gospel (that is, the announcement of the approach of this new state of things) must first be published in all nations.[32] Then the sun and moon would be darkened and the stars fall; the Son of man would come in power and glory, and gather his elect from all parts of the earth. The existing generation was not to pass till all these things were done. Not even the Son knew when this would happen; but as it might come suddenly and unexpectedly upon them, they were to be continually on the watch (Mk. xiii.; Mt. xxiv). The apostles would not even finish the cities of Israel before the Son of man had come (Mt. x. 23). Little is said in description of the nature of the kingdom of heaven except by the method of illustration. The main result to be gathered from numerous allusions to it is that justice is to prevail. Thus, the kingdom of heaven is said to be like a man who sowed good seed in his field, but in whose property an enemy maliciously mingled tares. At the harvest the tares are to be burnt, and the wheat gathered into the barn. This parable Jesus himself explained. The tares are the wicked; the wheat represents "the children of the kingdom." And as tares are burnt, so "the Son of man shall send his angels, and collect from his kingdom all offenses, and those who do wickedness, and shall throw them into the furnace of fire; there shall be weeping and gnashing of teeth. Then the just shall shine out like the sun in the kingdom of their Father." The same idea is expressed in the illustration of the net cast into the sea, which gathers good fish and bad. Just as the fishermen separate these, so the angels at the end of the world will separate the wicked from the midst of the just. Other comparisons represent the influence on the heart of faith in the kingdom. Thus, the kingdom of heaven is like a grain of mustard seed, which, though the smallest of seeds, becomes the largest of herbs. Or it is like leaven leavening three measures of meal. Again, it is like treasure hid in a field, or a pearl of great price (Mt. xiii. 24-50). The best qualification for preëminence in the kingdom was humility.