The world of ideas or thoughts. It is the most subtle of the three worlds, or the closest one to Omnipresence. The other worlds are the physical world and the astral world, or world of energy, which souls go to after physical death and before reincarnating into a physical body.
Beings who live in the causal world do not have physical bodies, they have causal bodies, instead made of thought. Only very advanced beings close to full realization live in the causal world. They do not eat anything, except the “manna of bliss,” according to Sri Yukteswar.
When one reaches this level, the desire for sense pleasure is nearly gone. Causal beings work out their desires by materializing them instantly. Souls in the causal world recognize one another as individualized points of joyous Spirit; their thought-things are the only objects which surround them. As a man, closing his eyes, can visualize a dazzling white light or a faint blue haze, so causal beings by thought alone are able to see, hear, feel, taste, and touch; they create anything, or dissolve it, by the power of cosmic mind.
Many beings remain for thousands of years in the causal cosmos. By deeper ecstasies the freed soul then withdraws itself from the little causal body and puts on the vastness of the causal cosmos. No longer does the soul have to experience its joy as an individualized wave of consciousness, but is merged in the One Cosmic Ocean.
In the words of Sri Yukteswar:
“Beings with unredeemed earthly karma are not permitted after astral death to go to the high causal sphere of cosmic ideas, but must shuttle to and fro from the physical and astral worlds only. Normal or long-established residents of the astral universe, on the other hand, pass to the infinitely finer and more delicate causal world. Shedding the thought-form of the causal body at the end of a certain span, determined by cosmic law, these advanced beings then return to a high astral planet, reborn in a new astral body to work out their unredeemed astral karma.
“Just as most people on earth have not learned through meditation-acquired vision to appreciate the superior joys and advantages of astral life and thus, after death, desire to return to the limited, imperfect pleasures of earth, so many astral beings, during the normal disintegration of their astral bodies, fail to picture the advanced state of spiritual joy in the causal world and, dwelling on thoughts of the more gross and gaudy astral happiness, yearn to revisit the astral paradise. Heavy astral karma must be redeemed by such beings before they can achieve after astral death a permanent stay in the causal thought-world, so thinly partitioned from the Creator.
“Only when a being has no further desires for experiences in the pleasing-to-the-eye astral cosmos, and cannot be tempted to go back there, does he remain in the causal world. Completing there the work of redeeming all causal karma or seeds of past desires, the confined soul thrusts out the last of the three corks of ignorance and, emerging from the final jar of the causal body, commingles with the Eternal.” [ref]Autobiography of a Yogi, Paramhansa Yogananda. Chapter 43, “The Resurrection of Sri Yukteswar.”[/ref]