roopam mahatte bahuvaktranetram mahaabaaho bahubaahooroopaadam |
bahoodaram bahudamshtraakaraalam drishtvaa lokaahaa pravyathitaastathaaham || 23 ||

Seeing your grand form with several mouths and eyes, O mighty armed, with several arms, thighs, feet and bellies, with fearful fangs, all beings are disturbed, and (so too am) I.
roopam : form
mahat : grand
te : your
bahuvaktranetram : with several mouths and eyes
mahaabaaho : O mighty armed
bahubaahooroopaadam : with several arms, thighs and feet
bahoodaram : with several bellies
bahudamshtraakaraalam : with fearful fangs
drishtvaa : seeing
lokaahaa : beings
pravyathitaahaa : disturbed
tatha : and
aham : I
Arjuna’s amazement turned into fear as he witnessed the transformation of Ishvara’s cosmic form. The “soumya roopa” or the pleasant form morphed into into the “ugra roopa”, the fear-inducing form. Shri Krishna’s kind, shining face was no more visible. It now was the face of a monster, with long sharp teeth that were “kaarala”, ready to take a bite.
When we see someone who has power but is benevolent and kind, we feel at peace. But when someone with power is clearly intent on causing destruction, we are afraid. When a general of a country army is disciplined and respects civilian authority, people are happy, otherwise he becomes a dictator and scares people. So therefore, seeing this terrible form of Ishvara, Arjuna saw that all beings in all of the worlds were cowering in fear of this form.
Why did Ishvara show this form to Arjuna? Didn’t Shri Krishna want everyone to remember his pleasant form only? There is a reason to this. Earlier, we learned about the tendency of our mind to demarcate certain aspect of the world as “good” or “bad”. But if we use the cosmic form as a means to meditate upon Ishvara, we need think like Ishvara. Ishvara comprises the entire creation where everything is necessary and everything has its place. We cannot demarcate anything good or bad. Only by discarding our prior conceptions of good and bad can we truly understand this terrible form of Ishvara.
What else about the form scared Arjuna? He continues in the next shloka.