"The physical powers of the body cannot be separated from the rationale of the mind and the emotions of the heart. They are one and the same, a compilation of a singular being. It is in the harmony of these three-body, mind, and heart- that we find spirit.
...
Spirit. In every language in all the Realms, surface and Underdark, in every time and every place, the word has a ring of strength and determination. It is the hero's strength, the mother's resilience, and the poor man's armor. It cannot be broken, and it cannot be taken away."
— R.A. Salvatore