Text 31
Transcendental Knowledge
917
This spirit is demonic, because demons do not believe in God but simply enjoy the property of the Supreme. Since there is a great need of an edition of the  Gītā  in English, as it is received by the  paramparā  (disciplic succession) system, an attempt is made herewith to fulfill this great want.  Bhagavad-gītā —accepted as it is—is a great boon to humanity; but if it is accepted as a treatise of philosophical speculations, it is simply a waste of time.
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स एवायं मया तेऽद्य योगः प्रोक्तः पुरातनः । भक्तोऽसि मे सखा चेति रहस्यं ह्येतदुत्तमम् ॥३॥
sa evāyaṁ mayā te’dya yogaḥ proktaḥ purātanaḥ bhakto’si me sakhā ceti rahasyaṁ hy etad uttamam
saḥ —the same ancient;  eva —certainly;  ayam —this;  mayā —by Me;  te —unto you;  adya —today;  yogaḥ —the science of  yoga ;  proktaḥ —spoken;  purātanaḥ —very old;  bhaktaḥ —devotee;  asi —you are;  me —My;  sakhā —friend;  ca —also;  iti —therefore;  rahasyam —mystery;  hi —certainly;  etat —this;  uttamam —transcendental.
TRANSLATION
That very ancient science of the relationship with the Supreme is today told by Me to you because you are My devotee as well as My friend; therefore you can understand the transcendental mystery of this science.
PURPORT
There are two classes of men, namely the devotee and the demon. The Lord selected Arjuna as the recipient of this great science owing to his becoming the devotee of the Lord, but for the demon it is not possible to understand this great mysterious science. There are a number of editions of this great book of knowledge, and some of them have commentaries by the devotees, and some of them have commentaries by the demons.