The whole Vedic knowledge is infallible. There are different examples how we take Vedic knowledge as infallible. Take for example, so far the Hindus are concerned, and how they accept the Vedic knowledge as complete, here is an insignificant example. Just like the cow dung. The cow dung is the stool of an animal. According to smṛti or Vedic wisdom, if one touches the stool of an animal he has to take his bath to purify himself. But in the Vedic scriptures the cow dung is as stated as pure. Rather, impure place or impure things are purified by touch of the cow dung. Now if one argues how it is that in one place it is said that the stool of the animal is impure and another place it is said that the cow dung which is also the stool of an animal, it is pure, so it is contradictory. But actually, it may appear to be contradictory, but because it is Vedic injunction, therefore for our practical purposes we accept it. And by that acceptance we are not committing mistake. It has been found by modern chemists, modern science, one Dr. Lal Mohan Gosal, he has very minutely analyzed the cow dung and he has found that cow dung is a composition of all antiseptic properties. So similarly, he has also analyzed the water of the Ganges out of curiosity. So my idea is that Vedic knowledge is complete because it is above all doubts and all mistakes. So, and Bhagavad-gītā is the essence of all Vedic knowledge. The Vedic knowledge is therefore infallible. It comes down through the perfect disciplic succession.
Therefore Vedic knowledge is not a thing of research. Our research work is imperfect because we are searching everything with imperfect senses. Therefore the result of our research work is also imperfect. It cannot be perfect. We have to accept the perfect knowledge. The perfect knowledge is coming down, as it is stated in the Bhagavad-gītā, just we have begun, evaṁ paramparā-prāptam imaṁ rājarṣayo viduḥ (BG 4.2). We have to receive the knowledge from the right source in disciplic succession of spiritual master beginning from the Lord Himself. So Bhagavad-gītā is spoken by the Lord Himself.