I really enjoy Nichiren’s view on the 10 Worlds in our daily lives:

As we often look at each other’s faces, we notice our facial expression changes from time to time. It is full of delight, anger, or calm sometimes; but other times it changes to greed, ignorance, or flattery. Anger represents hells; greed—hungry spirits; ignorance—beasts; flattery—asura demons; delight—gods; and calm—men. Thus, we see in the countenance of people six realms of illusion, from hells to the realm of gods. We cannot see four realms of holy ones (śrāvaka, pratyekabuddha, bodhisattvas, and Buddhas), which are hidden from our eyes. Nevertheless, we must be able to see them, too, if we look for them carefully.

Kanjin Honzon-shō, A Treatise Revealing the Spiritual Contemplation and the Most Verable One, Writings of Nichiren Shōnin, Doctrine 2, Page 134-135

Recently I’ve been puzzling over how to see the four higher worlds, what it means to be in the realm of śrāvaka or pratyekabuddha or bodhisattva or buddha.
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Actually, buddhahood is the easiest. That’s where we are every time we chant Namu Myōhō Renge Kyō:

It is said that the merit of all the Buddhist scriptures (except the Lotus Sūtra) is found in the promise that men can become Buddhas after they have done good deeds, which means the attainment of Buddhahood is not certain. In the case of the Lotus Sūtra, however, when one touches it, one’s hands immediately become Buddhas, and when one chants it, one’s mouth instantly becomes a Buddha. For example, when the moon rises above the eastern mountain, its reflection immediately shows on the water. Sound and resonance also occur simultaneously.

Ueno-dono Gozen Gohenji, Reply to My Lady, the Nun of Ueno, Writings of Nichiren Shōnin, Followers II, Volume 7, Page 58-59

And every time we practice for others as we seek our own enlightenment we enter the realm of bodhisattvas.

As for the other two higher realms, why not describe it like this:

• Śrāvakas: When we hear the Dharma and study Buddhism we are in the realm of Śrāvakas.
• Pratyekabuddhas: When we put into practice for ourselves what we have learned we enter the realm of Pratyekabuddhas.

I asked Ryuei Shonin about my idea and this was his response:

All four higher realms involve practice though – but in different ways. I’d put it more like this:

Śrāvaka: When we hear the Dharma and understand the pervasiveness of suffering, begin to eradicate its causes, realize for ourselves the lessening of suffering, and continue to cultivate the eightfold noble path.

Pratyekabuddha: When we deeply contemplate the causal and conditioned nature of phenomena, in particular the causality of our own life in order to free ourselves from habitual patterns.

The difference between the Śrāvaka and Prayekabuddha is that, as it says in the Infinite Meanings and Lotus Sutra, the former practices the four noble truths (and eightfold path) while the latter contemplate the twelve-fold chain of dependent origination. The former are practicing a very practical and relatively simple path laid out by the Buddha (like following the 12 steps if you’re in AA), while the latter are thinking through all the implications of dependent origination for themselves. The latter takes a more philosophical mind and more self-reflection.

Bodhisattvas: The six perfections overlap a great deal with the eightfold path, but what is different is the explicit addition of generosity and patience. However, the Śrāvakas or voice-hearers do also teach the four noble truths to others. The real difference is that bodhisattvas have bodhicitta, a higher aspiration that involves remaining in the world of suffering (requiring patience) to build up the merit and wisdom so that they can attain buddhahood and thereby be able to share the Dharma most effectively with others (which is generosity of course). But note that this does not mean they will necessarily teach more than Śrāvakas. A beginner bodhisattva may not even be as good a teacher as a śrāvaka like Shariputra, but their aspiration is more all-encompassing even if they realize they have to mind their own business and build up their own practice and wisdom before presuming to teach others. We should be careful not to equate bodhisattvas with evangelicals who try to convert others before they have even fully transformed themselves.

Buddhas: One word that Tiantai uses for the Perfect teaching I find very striking – “uncontrived” (J. musa; 無作). What this means is that the Buddha’s actions are spontaneous unselfconscious and thoroughly authentic responses to every situation. Furthermore, as masters of skillful means they appear in and through the other nine worlds.

I like my summary:

• Śrāvakas: When we hear the Dharma and study Buddhisms we are in the realm of Śrāvakas.
• Pratyekabuddhas: When we put into practice for ourselves what we have learned we enter the realm of Pratyekabuddhas.
• Bodhisattvas: When we seek to help all others to gain what we have gained from learning about Buddhism and putting it into practice, then we enter the realm of Bodhisattvas.
• Buddhas: This is the realm we enter when we chant Namu Myōhō Renge Kyō, merging what we have learned and what we practice while seeking to have all others join this path.

But that’s not doctrinal and perhaps potentially misleading.

As Ryuei cautioned during our email exchange:

Bottom line, you can’t and probably shouldn’t try to easily reduce the higher worlds to a simple image or concept like you can with the lower worlds.

See Experiencing The Interpenetrating Ten Worlds