Atma is enveloped within five sheaths, known as Panchakoshas. As you go inward, these sheaths become more subtle. The two conditions of subtlety are control and pervasiveness. That is, if A controls B and A pervades B, then A is considered subtler than B. Applying this logic to the sheaths, we determine their order from the grossest to the subtlest as follows: Food Sheath, Vital-Air Sheath, Mental Sheath, Intellectual Sheath, Bliss Sheath. The food sheath corresponds to the gross body. The next three sheaths relate to the subtle body. The Bliss sheath corresponds to the causal body. Atma remains untouched by these sheaths.