aprakaso ’pravrttis ca
pramado moha eva ca
tamasy etani jayante
vivrddhe kuru-nandana

"When there is an increase in the mode of ignorance, O son of Kuru, darkness, inertia, madness and illusion are manifested."

Kuru-nandana = Arjuna [ of Kuru dynasty]. Since Arjuna was born in this great dynasty, he should develop only satva quality and discard the other two. He is to bring happiness [ananda] to himself and his dynasty and so he should listen to the Lord. The following are the symptoms of a person with tamo quality:

  1. Aprakasa = without brightness, or darkness, indicating lack of knowledge. Swami Ramanuja says it means Gyana anudaya or knowledge not born.
  2. Apravrtti = not engaged in [any] action [laziness].
  3. Pramada = carelessness, preventing performing our duties prescribed and to be done at a scheduled time.
  4. Moha = delusion, understanding things in confused way. Here, though knowledge is born, confusion exists. It is viparita Gyana, where we mistake one for another.
Etani = all these [defects] are, tamasi = in tamas quality, vivrddhe = when well developed, jayante = exhibited. Defect in knowledge is in Three categories:
  • Gyana anudayam - not understanding the matter. He will not know what Vedas and Puranas have told. He will not know what are his duties. We might not know many things. It hardly matters; but to know what is good for oneself has to be known. Not knowing this is aprakasa.
  • Annasa Gyana - one sees the matter but understands its quality wrongly. For example, understanding the white color of conch as yellow due to defect in the eyes.
  • Viparita Gyana - here the matter is understood differently, like thinking a rope to be snake.
Here we should not worry about not knowing so many things in this World. We might not know the mechanisms of many things like automobile or watch, etc. These are not Gyana anudaya, and the Lord does not mean this. He talks about Gyana about atman and Paramatman. We should know who we are and what is our destination. When tamo quality develops any of the Four defects mentioned, are exhibited. Thus the Lord tells Arjuna the symptoms of satva, rajas and tamas qualities. With these symptoms we can diagnose our quality and take remedial action. This way we can develop satva quality and eliminate rajo and tamo qualities.