Why did Shrīkrushṇa narrate Gitā only to Arjun?

Arjun was Gudakeshā  (v) that is the one who could comprehend the implied meaning (gudha means secret) in Keshav’s (Shrīkrushṇa’s) speech. At the beginning of the Shrīmadbhagwadgitā, Arjun tells Shrīkrushṇa, ‘Senayorubhayormadhye ratham sthapaya me chyut (सेनयोरुभयोर्मध्‍ये रथं स्‍थापय मेऽच्‍युत|)’ (Shrīmadbhagwadgitā 1:21). It means ‘O Achyut, place my chariot in the midst of both the armies’. Here, of the several Names of Shrīkrushṇa,  Achyut is used because Arjun is referring to the Shrīkrushṇa who does not deflect from His responsibilities, the one who is unflinching. ‘In the midst of both the armies’ implies between the good and the evil. Thus He asks Shrīkrushṇa to take him beyond all kinds of duality. Click here to read more.

• The Mahābhārat and the Shrīmadbhagwadgitā