The Talmud says that a student who has qualified as a teacher and does not teach transgresses ‘Thou shalt not kill’, and the opposite is true as well; a person who is not qualified to teach and teaches - also transgresses ‘Thou shalt not kill’. This is why the niqqud vowels on ‘Thou shalt not kill’ sometimes have a dot in the patach (open) and sometimes in the kamatz (closed). This hints that ‘Thou shalt not kill’ applies to a person who has qualified to teach and keeps his mouth 'closed' without teaching, and to a person who has not qualified as a teacher and teaches – 'opens' his mouth. That is why there is a dot in both the patach and the kamatz. What is the reason behind the transgression? The attribute of pride, the worst of attributes in all transgressions. For the right thing is that one who has attained qualification to teach should teach others. But the person does not teach - out of pride; and the one who has not qualified and must learn from others does not wish to do so - out of excess pride. The remedy to their ills is to transform pride into modesty; once they have become humble the one who has qualified to teach will teaches others, and the one who has not qualified will not, and must learn from others.