The mer kaba means Beloved Soul, ka meaning vital essence, making a difference between the living and dead body, as well as it means double, as in dualistic dichotomy of nature, and ba is personality i.e. love of the heart (ib).
The soul for ancient Egyptians was made up of seven parts, three immortal (Ren, Sekhem, and Akh / Akhu / Khu / Ikhu, and four mortal parts (Ka, Ba, Ib / Ab, and Shut / Khaibit), as well as two bodies, physical Khet / Khat / Kha and spiritual Sah.
http://www.touregypt.net/featurestories/soul.htm
https://en.m.wikipedia.org/wiki/Ancient_Egyptian_conception_of_the_soul
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