Why the injunction against sudras studing the Vedas?

For understanding the meaning of shastras,one must have a well-cultivated moral sensibility and experience in the practise of their truths.The injunction against sudras studing the vedas is not altogther unjustified. A sudra,in other words,a person without moral education,with out sense and without knoledge,would completely misread the shastras.No person,even if grown up in age,is qualified to understand difficult problems in algebra without preparqation.Before anyone can undestand such problems,he must have studied the elements of the subject.How would 'Aham Brahmasmi'souns in the mouth of a lustful man?what meaning,or distorted meaning,would he not attach to it?Hence,anyone who offers to interpret the shastras must have observed the prescribed disciplined in his life.A mechanical observance of these disciplines is as futile as it is difficult.The shastras regard it essential that one shoul have a guru.