Three bodies are not only considered as a spiritual context, we can also view it in another dimension of physics, psychology as well as in our own dimension based on the needs makes this topic also one of the most interesting of all times. They are Physical, Astral and Causal
Physical body: We all can see and know our physical body made up of the five elements such as Air, Water, Fire, Earth, and Ether by the reproductive process of humans. After birth, this body will grow and to retain the life process, there is a need for additional nutrients made up of the same five elements in the form of food. It also gets matured with time. Finally, after death, the physical body is decomposed.
Astral body: The astral body is also known as the subtle body made up of the vital force representing our mind and intellectual qualities which is responsible for the physiological functions of our body. It has been functioning and felt by the consciousness in the form of Touching sensation (air), Vision (fire), Taste (water), Hearing the sound (Ether), Smell (Earth) by our physical body. We can also feel the astral body in lucid dreams without a physical body is said as astral projection or out of body experience.
Causal body: It is considered as the deeper mind which we are not aware of it by our physical body directly, but by our deep sleep or at the level of super consciousness, we can feel it from the astral body and it has been realized by our physical body consciousness too later by acquiring the knowledge from the source of causal body which has been gained from previous forms of us in this universe.
Our whole life is experienced by the three bodies directly or indirectly by us. Where physical body depends on the food and other essential elements for survival it never retains for long. With thoughts and feelings, it can survive more, but to express there is a need for the physical body. Most super conscious peaceful source of knowledge attributes retains as long to get a new form in the universe.