Arjuna’s  desire to survey the two armies

atha  vyavasthitaan drishtwaa dhaartaraashtraan kapidhwajah
pravritte  shastrasampaate dhanurudyamya paandavah   // 20 //
hrisheekesham  tadaa vaakyamidamaaha maheepate - 21

Then, O Lord of the earth, seeing Dhritarashtra's men  being positioned and discharge of weapons about to begin, Pandava (Arjuna),  whose ensign was Hanuman, raising his bow, spoke the following words to  Krishna.

The  critical situation prevailing just at that moment when the war was about to  begin was described.  The hero of  Mahabharata war, Arjuna, arrived at the battlefield.  Tension prevailed everywhere.  Crisis was at its zenith.

Arjuna  appeared impatient to fire the shot.  He  raised his bow to position it and at that crucial juncture he spoke to Krishna  the following words which turned out to be historic as the starting point for  the dialogue between them in the form of the great Srimad Bhagavad Gita.

arjuna  uvaacha
senayor  ubhayormadhye ratham sthaapaya me'chyuta   // 21 //
yaavad etaan  nireekshe'ham yoddhukaamaan avasthitaan
kair mayaa  saha yoddhavyam asmin ranasamudyame  //  22 //

Arjuna said
O Achyuta (Krishna) place my chariot in between  both the armies so that I may survey those who stand here eager to fight.  Let me know on the eve of this battle with  whom I have to fight.

yotsyamaanaan  avekshe'ham ya ete'tra samaagataah
dhaartaraashtrasya  durbuddher yuddhe priyachikeershavah // 23 //

For, I desire to have a glance at those who are  assembled here to fight, wishing to please the perverted son of Dhritarashtra.

Arjuna  thus expressed his bravery, readiness, impatience, gallantry and determination  to face the battle.  This is an important  stage in the story because up to this time Arjuna was an invincible hero full  of self-confidence and enthusiasm with no signs of mental aberrations. However,  a little later he became a completely changed personality.

Sri  Krishna enters the scene
   
  sanjaya  uvaacha
  evamukto  hrisheekesho gudaakeshena bhaarata
  senayor  ubhayormadhye sthaapayitwaa rathottamam // 24 //
  bheeshma  drona pramukhatah sarveshaam cha maheekshitam
  uvaacha  paartha pashyaitaan samavetaan kuroon iti   // 25 //

Sanjaya said
O Bharata (Dhritarashtra), thus requested by  Gudakesha (Arjuna), Hrishikesha  placed  the magnificent chariot between the two armies in front of Bhishma and Drona  and the other rulers of the earth and said `O Partha (Arjuna), behold all these  Kurus assembled here'.

Gudakesha,  one who has controlled sleep i.e. Arjuna. It implies that once a goal is set by  him he will not rest contended till it is achieved.  Partha means the son of Prtha (Kunti) i.e.  Arjuna. Krishna placed his chariot with sagacity at such a point wherefrom  Arjuna could see clearly his kinsman, Bhishma and preceptor, Drona and other  kings and warriors of Kaurava side.

As  a dutiful driver Krishna told Arjuna `Behold, O Arjuna, all the Kauravas  gathered here'.  These are the only words  spoken by Krishna in the first chapter of the Gita which proved to be a spark  to ignite the process of burning down the false perceptions of the mighty  Arjuna.

What  did Arjuna see?

tatraa  pashyat sthitaan paarthah pitrin atha pitaamahaan
aacharyaan  maatulaan bhraatrun putraan pautraan sakheemstathaa //26 //

Then Arjuna saw stationed there in the armies, uncles,  grandfathers, teachers, maternal uncles, brothers, sons, grandsons and friends  too.

shvashuraan  suhridashchaiva  senayorubhayorapi
taan  sameekshya sa kaunteyah sarvaan bandhoon avasthitaan //27 //
kripayaa  parayaa'vishto visheedannidam abraveet - 28

He saw fathers-in-law and friends also in both  armies.  Kaunteya (son of Kunti) i.e.  Arjuna seeing all these relatives arrayed there, became overwhelmed by supreme  compassion and said this sorrowfully.

Arjuna  seeing his elders and other relations, teachers, friends and well wishers  arrayed in the battle ready to fight suddenly developed extreme self-pity and  compassion.  His manliness gave way to  faint-heartedness thinking about consequences that will follow in waging the  war with his kinsmen which will result in destroying his own race.

The  valiant hero, Arjuna, transformed himself into a kinsman of the opposite side  i.e. as a son, a brother, a student etc.  This change of disposition was verily  spontaneous. It was not due to any discrimination, but on account of the very  absence of it and because of an erroneous understanding called delusion and  mental confusion called grief which prevents right perception of the situation.