The simplest concept is Ren, which is literally your name: it lives for as long as you are remembered, or can be read about on inscriptions, or included in prayers for the ancestors and their achievements. Ka is also easy enough to translate into modern idiom, for it is that vital essence that makes the difference between the living and the dead, between life and dead meat, between a warm body and cold clay.
Ib is literally the heart, formed from a single drop of clotted blood extracted from your mother’s heart at the hour of your conception or birth. By heart, the Egyptians meant not just the organ for pumping blood around your body, but the seat of your soul, the good directing force in your life, searching after truth, peace, and harmony.
Ba is that which makes each of us unique and different, that which makes us strive and achieve, the motivator but also the hungry elemental force that needs food and sex. In some form, your ba is destined to survive after death, often depicted or imagined as a human-headed bird, which with good fortune will go forth by day to enjoy the light, but might also end up existing only in the dark, like the bat or the ruin-haunting owl. Sheut is your shadow, and by extension the other you, as well as being used to describe a statue, a model, or a painting of a human.”
Excerpted from: Rogerson, Barnaby. Rogerson’s Book of Numbers: The Culture of Numbers–from 1,001 Nights to the Seven Wonders of the World. New York: Picador, 2013.