Answer

In Jain philosophy, the Loka is the inhabited universe. It is said to be 14 rajju high in total, and it is divided into three worlds:

1. Urdhva Loka — upper world
2. Madhya Loka — middle world
3. Adho Loka — lower world

Beyond the Loka is Aloka, which is empty space and has no living beings.

Explanation

1) Meaning of 14 Rajju

• Rajju is a very large cosmic unit used in Jain cosmology.
• The full height of the Loka is described as 14 rajju.
• This means the universe is finite, not endless.
• It has a definite shape and boundary.

2) Shape of the Loka

• The Loka is often described as having the shape of a standing human figure.
• It is narrower in the middle and broader above and below.
• In traditional diagrams, it resembles a person standing straight, with the middle part like the waist.
• This is why Jain cosmology often uses the image of Lokapurusha.

3) The Three Lokas in Detail

Urdhva Loka — Upper World

This is the realm above the middle world.

• It contains the heavenly abodes of devas.
• It is the region of Vaimanika devas.
• At the very top of the Loka is Siddhashila, the abode of liberated souls.
• The upper world is considered a realm of great happiness, subtle existence, and higher celestial states.

Main features:

• Heavenly beings
• Higher spiritual purity than the lower worlds
• Siddhas at the summit

Madhya Loka — Middle World

This is the central world where humans live.

• It includes the world of human beings, animals, plants, and many other life forms.
• It contains the Jambudvipa and other continents and oceans described in Jain cosmology.
• The sun, moon, stars, and planets are also placed in this middle region.

This world is spiritually very important because:

• Human birth is considered highly valuable.
• Moksha is possible through right faith, right knowledge, and right conduct.
• It is the field where karma can be purified through discipline, vows, and tapa.

Adho Loka — Lower World

This is the region below the middle world.

• It contains the seven hells.
• It is the abode of naraki beings, who experience intense suffering due to heavy karmas.
• The lower world is described as dark, painful, and full of misery.

The seven hells are traditionally named:

• Ratnaprabha
• Sharkaraprabha
• Valukaprabha
• Pankaprabha
• Dhumaprabha
• Tamahprabha
• Tamatamahprabha

Each deeper hell has greater suffering than the one above it.

Spiritual Understanding

Jain cosmology teaches an important spiritual truth:

• The universe is ordered and bounded.
• Every soul travels through different states according to karma.
• Urdhva Loka shows the possibility of higher existence.
• Madhya Loka is the most precious place for spiritual effort.
• Adho Loka reminds us of the painful results of intense karmic bondage.

The greatest message of this teaching is:

• Use human life wisely.
• Live with non-violence, restraint, truth, and purity.
• Move toward liberation, not bondage.

Takeaway

The Jain view of the universe is deeply spiritual:

• 14 rajju shows the Loka has a fixed cosmic size.
• Its shape is like a human form.
• The three worlds are upper, middle, and lower.
• Among them, Madhya Loka is the most important for spiritual progress because liberation is attained through right conduct here.

If you want, I can also give you a simple diagram-style explanation of Loka in easy English.