SB 3.6.4

prabuddha-karmā daivena
 trayoviṁśatiko gaṇaḥ
prerito ’janayat svābhir
 mātrābhir adhipūruṣam
Word for word: 
prabuddha — awakened; karmā — activities; daivena — by the will of the Supreme; trayaḥ-viṁśatikaḥ — by the twenty-three principal ingredients; gaṇaḥ — the combination; preritaḥ — induced by; ajanayat — manifested; svābhiḥ — by His personal; mātrābhiḥ — plenary expansion; adhipūruṣam — the gigantic universal form (viśva-rūpa).
Translation: 
When the twenty-three principal elements were set in action by the will of the Supreme, the gigantic universal form, or the viśvarūpa body of the Lord, came into existence.
Purport: 

The virāṭ-rūpa or viśva-rūpa, the gigantic universal form of the Lord, which is very much appreciated by the impersonalist, is not an eternal form of the Lord. It is manifested by the supreme will of the Lord after the ingredients of material creation. Lord Kṛṣṇa exhibited this virāṭ or viśva-rūpa to Arjuna just to convince the impersonalists that He is the original Personality of Godhead. Kṛṣṇa exhibited the virāṭ-rūpa; it is not that Kṛṣṇa was exhibited by the virāṭ-rūpa. The virāṭ-rūpa is not, therefore, an eternal form of the Lord exhibited in the spiritual sky; it is a material manifestation of the Lord. The arcā-vigraha, or the worshipable Deity in the temple, is a similar manifestation of the Lord for the neophytes. But in spite of their material touch, such forms of the Lord as the virāṭ and arcā are all nondifferent from His eternal form as Lord Kṛṣṇa.