Itihasa means history. The Vedic system of itihasa, it is not the modern history. Itihasa means some incidence which took place long, long ago, and such incidence is very beneficial to hear so that we can follow. That is called itihasa. It is not chronological record of all incidences. Only important things. Puratanam. Puratanam means old and important. So Sukadeva Gosvami is explaining to Pariksit Maharaja how important is Krsna consciousness. Now he is giving one incidence of history — example is better than precept — how Ajamila was saved simply by chanting once — not once, many times — "Narayana." That is the itihasam puratanam.
In the Vedic literatures there are itihasas, or histories. Just like Mahabharata. Mahabharata is the history.
Everything in the sastra we should follow. This is called brahminical culture. This Krsna consciousness movement means brahminical culture — the cultural exhibition of the first-class men. First-class men. The brahmana is to be understood as the first-class man within the human society. Therefore Krsna says, catur-varnyam maya srstam guna-karma-vibhagasah [Bg. 4.13].
Itihasa, history, history means to understand the activities of the first-class man. That is history. They pick up the most important incidences. Therefore the example is given here that udaharanti imam itihasam puratanam. Because it is a first-class incidence… Otherwise, if you record the history of the whole period, then who will read that, and who will appreciate that, and where you will keep that? Daily so many things are happening. Therefore, according to Vedic system, the only important incidences are recorded in the history. Therefore it is called Purana. Purana means old history. Puratanam. Puratanam means very, very old that are recorded. So this Srimad-Bhagavatam is the collection of very old history, historical incidence. Itihasa purananam saram saram samuddhrtya[?]. Saram means essence. Not that all nonsense records have to be taken. No. Saram saram, only the important, essence, that are to be recorded. This is called Indian history. Mahabharata. Maha means Greater India. Greater India, there were so many incidences were there, but the most important incidence, the Battle of Kuruksetra, is there. Not that all the battles should be recorded.
So one Ajamila was delivered by chanting Narayana's name. You can deliver many millions of Ajamila. The process is the same. The process has not changed. Therefore he is quoting that itihasam atra codaharanti imam itihasam puratanam. It is spiritual. It is not that now the mode has changed. No. What was potent millions of years ago, that is potent still. That is spiritual. It does not change. Therefore it is said, itihasam puratanam. Although it is very old, but the effect is the same, effect is the same. In the old times people used to eat and get satisfaction; the same satisfaction is now also. You eat, you feel satisfaction. Eating, sleeping, mating and defending — this is the material necessities. So the such necessities were in the old, millions of years ago, and those necessities are still there. It is no change actually.
From Srila Prabhupada's lecture on Srimad-Bhagavatam 6.1.20 — July 4, 1975, Chicago