ऊर्ध्वं गच्छन्ति सत्त्वस्था मध्ये तिष्ठन्ति राजसाः।
जघन्यगुणवृत्तिस्था अधो गच्छन्ति तामसाः।।14.18।।
।।14.18।। सत्त्वगुण में स्थित पुरुष उच्च (लोकों को) जाते हैं राजस पुरुष मध्य (मनुष्य लोक) में रहते हैं और तमोगुण की अत्यन्त हीन प्रवृत्तियों में स्थित तामस लोग अधोगति को प्राप्त होते हैं।।
Now Lord Krishna reveals that those who are situated in sattva guna or the mode of goodness ascend upward in spiritual devlopement and eventually achieve moksa or liberation from material existence. Those who are situated in raja guna or the mode of passion have the desire for rewards for thecause of actions engage in activities that give them the results they wish to exploit and enjoy. Maintaining this mentality they engage fully in such fruitive activities life after life and are born again and again to engage in more and more works. Hence since it insures a constant reoccurrence of material births it is full of misery. Those who are situated in tama guna or the mode of ignorance are engaged in degenerative behaivior and descend downwards doing more and more despicable inhuman activities. Such beings development is in retrograde and after becoming the lowest types of humanity such as cannibals and perverts of beastiality they sink into the animal species themselves. After that due to the reactions from their heinious activitie they become worms and maggots and then they even descend into the lowest of plants to become stationary creepers and fungus.So Lord Krishna has revealed how the jiva or embodied being rises in evolution and how it descends. All those who adopt and maintain a strict vegetarian diet as detailed in chapter 6, verse 17 and chapter 17 verse 8 and who perform activities as a matter of duty without impetus for rewards gradually become fully situated in sattva guna and eventually ascend performing all activities for the satifaction for the Supreme Lord.
