In this verse it appears that Arjuna is already satisfied with his understanding of the Supreme Lord Krsna. By Krsna's grace, Arjuna has personal experience, intelligence and knowledge and whatever else a person may have through all these agencies, and he has understood Krsna as the Supreme Personality of Godhead. For him there is no doubt, Yet he is asking Krsna to explain His all-pervading nature so that in the future people will understand, especially the impersonalists, how He exists in His all-pervading aspect through His different energies. One should know that this is being asked by Arjuna on behalf of the common people.