Srila Prabhupada:
So the modern psychologists, they have divided the function of the mind: thinking, feeling, willing, and then other subdivisions. That is known as the science of psychology. But intelligence... Above mind there is intelligence. I don't think in the modern science there is any analytical study of the intelligence function. But in the Vedic literature there is analysis of the intelligence. They are described here: samsaya, doubtfulness.
In the Bhagavad-gita there is a statement: "Those who are doubtful about the existence of God," vinasyati, "they are finished." Their progress is finished. That niscayatma, that is very good, to believe, to have faith, niscaya, by full assertion. Just like Krsna said, sarva-dharman parityajya mam ekam saranam vraja [Bg. 18.66]. So if by your intelligence you become doubtful, "Whether Krsna is able to give me protection?" then you are finished. Samsayatma vinasyati. But if you have faith in Krsna's words, niscaya, "When Krsna says that if I surrender unto Him, He will give me protection, there is no doubt about it," that is called faith. Niscayatmika. Vyavasayatmika buddhih. Buddhi, intelligence, that is very good.
Avyavasayinam, those who have no faith, doubtful, they have got different branches of activities. But one who has got faith, niscayatmika, "Yes, here Krsna says that He will give me protection. Let me surrender," then his life becomes successful. This is beginning of successful life. Adau sraddha, this araddha, or this niscayatmika buddhi, or vyavasayatmika buddhi, is the beginning of spiritual life. If one has no faith in the words of the authorities, then he has no hope.
