The Fivefold Soul
The five names are ancient: the midrash Genesis Rabbah (14:9) already calls the one soul nefesh, ruach, neshamah, chayah and yechidah. What grew over time was their ranking: earlier Kabbalah knew only three levels of the soul, and later Kabbalists, above all the sixteenth-century Lurianic school, made chayah and yechidah two higher levels.
Genesis Rabbah 14:9; Gershom Scholem, 'Gilgul: The Transmigration of Souls', in On the Mystical Shape of the Godhead (German 1962; English 1991); Chaim Vital, Sha'ar ha-Gilgulim, Introduction 1
A Kabbalistic model dividing the human soul into five distinct ascending levels, each representing a deeper degree of spiritual attainment.