This classic saying from the New Testament (Matthew 7:16) confronts effect and cause. A bad effect is not likely to have a good cause, and vice versa. Thorns do not bear grapes, and we find no figs on thistles. We should therefore not rely on fine words and theories. What counts are the effects that arise from them.
An important, perhaps the most important, task of a good teacher is to dissuade students from making hasty judgments, for it is with this craving that we come into the world, while on the contrary reason only develops very slowly. Infants immediately start crying when they feel unwell and they smile when being treated kindly. But the vocabulary of pubescent young people still contains mainly expressions like super, cool, great or negative ones like poo, disgusting, evil etc. The aversion to independent thinking and the tendency to replace arguments with hasty values and judgments remains in later life – for many people throughout their lives.