KATHOPNISHAD CHAPTER 3 SHLOKA 7

                                                           यस्त्वविज्ञानवान्भव

                                                       त्यमनस्कः सदाऽशुचिः । 

                                                         न स तत्पदमाप्नोति

                                                        संसारं चाधिगच्छति ॥ ७

                                             TASTU AVIDNYANVAN BHAVATI

                                             AMANASKAHA SADA ASUCHIHI |

                                               NA SA TAT PADAM APNOTI 

                                          SAUSARAM CHA ADHIGACHHATI ||7

      ONE WHO DOES NOT HAVE PROPER KNOWLEDGE,THOUGHTS,AND PURITY,

         NEVER ATTAINS THAT LEVEL-GOAL, AND GETS IN TO THE SAUSARA

                                   ( OF BIRTH AND DEATH CYCLE)||7

 In scriptures we have continuation of the same message in different forms or examples. Here in this Shloka we are told by Yamaraj that there are people who may seem to talk certain things that may be impressive and we may think that they have conquered the Death and Birth cycle. But in reality unless one has done certain things he or she will not get freedom from this Suansara where every thing is mortal. He is telling us the characters of some one who will achieve the goal  and will be free of death and birth cycle. So when one does not have the knowledge -and by proper knowledge he is not talking about physics or chemistry or biology but about something beyond the external appearance or things that can be perceived by sense organs . The entire science is devoted to findings more and more about things that can be perceived by our senses. We have made great progress in that direction. We did not know about atoms and then subatomic particles with microscopes or farther galaxies that are seen with telescope - but all of this is still dependent upon senses . We can do chat on phone or do video call and again that is sense dependent. But here we are not talking about that Knowledge. The real KNOWLEDGE is beyond the senses. Some people classify this as Gross-STHULA, Subtle -SUKSHMA , , SHUNYA and then SHIV , as 4 different levels . Shunya does not mean NOTHING but it is Nothing that can be perceived by senses. So when one has that knowledge then he is DNYANI. Proper thoughts  and purity of mind and action is also needed. Many may have it in OUTSIDE life  and behavior but not INSIDE. Such person may have read scriptures and understood them  and may have practiced them , but unless he has all the things that are mentioned above , he will not have freedom from mortal world.