Verily beareth fruit (dh karpoporei). Who in reality (dh) does bear fruit (cf. Matthew 7:16-20 ). The fruit reveals the character of the tree and the value of the straw for wheat. Some grain must come else it is only chaff, straw, worthless. The first three classes have no fruit and so show that they are unfruitful soil, unsaved souls and lives. There is variety in those who do bear fruit, but they have some fruit. The lesson of the parable as explained by Jesus is precisely this, the variety in the results of the seed sown according to the soil on which it falls. Every teacher and preacher knows how true this is. It is the teacher's task as the sower to sow the right seed, the word of the kingdom. The soil determines the outcome. There are critics today who scout this interpretation of the parable by Jesus as too allegorical with too much detail and probably not that really given by Jesus since modern scholars are not agreed on the main point of the parable. But the average Christian sees the point all right. This parable was not meant to explain all the problems of human life.