In Yoga philosophy there are the five koshas. These five koshas are layers or sheaths which make us whole.
The outermost kosha is Anna Maya kosha which is the physical body.
The next kosha or layer is our vital energy. The most obvious part here is breath. This kosha is called Prana Maya kosha.
The next layer is the Mano Maya kosha. This is our mind. It is our thoughts and feelings. During meditation or Yoga Nidra we can speak to this kosha by using opposites. This can help the mind to learn flexibility. The mind works better when it has flexibility because we do not find ourselves getting stuck in unhealthy thoughts or feelings. Instead we can be comfortable knowing that all the thoughts we have are temporary. Thoughts and feelings come and go.
The next layer is Vijnanamaya kosha which relates to a collective consciousness and our wisdom.
The innermost kosha which is peace, stillness. This is called Ananda Maya kosha.