This is an excerpt from the preface of the Bhagavad-gita As It Is, translated and commented upon by His Divine Grace A.C Bhakivedanta Swami Prabhupada. Herein His Divine Grace explains why hearing from a person in the proper succession of understanding the science of Bhagavad-gita is so important.
If personally I have any credit in this matter, it is only that I have tried to present Bhagavad-gita as it is, without any adulteration. Before my presentation of Bhagavad-gita As It Is, almost all the English editions of Bhagavad-gita were introduced to fulfill someone's personal ambition. But our attempt, in presenting Bhagavad-gita As It Is, is to present the mission of the Supreme Personality of Godhead, Krsna. Our business is to present the will of Krsna, not that of any mundane speculator like the politician, philosopher or scientist, for they have very little knowledge of Krsna, despite all their other knowledge. When Krsna says, man-mana bhava mad-bhakto mad-yaji mam namaskuru [Bg. 18.65], etc., we, unlike the so-called scholars, do not say that Krsna and His inner spirit are different. Krsna is absolute, and there is no difference between Krsna's name, Krsna's form, Krsna's qualities, Krsna's pastimes, etc. This absolute position of Krsna is difficult to understand for any person who is not a devotee of Krsna in the system of parampara (disciplic succession). Generally the so-called scholars, politicians, philosophers, and svamis, without perfect knowledge of Krsna, try to banish or kill Krsna when writing commentary on Bhagavad-gita. Such unauthorized commentary upon Bhagavad-gita is known as Mayavada-bhasya, and Lord Caitanya has warned us about these unauthorized men. Lord Caitanya clearly says that anyone who tries to understand Bhagavad-gita from the Mayavadi point of view will commit a great blunder. The result of such a blunder will be that the misguided student of Bhagavad-gita will certainly be bewildered on the path of spiritual guidance and will not be able to go back to home, back to Godhead.
-Srila Prabhupada, Bhagavad-gita preface