The blood, and more specifically the liver.
See if this linked page helps.
nefesh yafah (× ×¤×© יפה)
The two parts of the soul according to Jewish philosophy are the Neshamah, which represents the highest level of the soul and connects to God, and the Nefesh, which represents the earthly and physical aspects of the soul responsible for basic life functions.
The heart.
nefesh nekhmada (× ×¤×© × ×—×ž×“×”)
nephash is not a Hebrew word, but it is close to nefesh (× ×¤×©) which means life force, and sometimes translated as soul.
Jewish tradition teaches of different parts or levels of the soul. The neshama is associated with the use of free-will and is centered in the brain. The ruach is associated with emotion and is centered in the heart. The nefesh is the spark of life, associated with physical function. If the body (even brain-dead) is alive, the nefesh is there.
According to Judaism, there are 5 levels of the soul, they are called: Nefesh, Ruach, Neshama, Chaya, and Yechida. Please see the related link for more detailed information.
Said to a male: "atah ha-neshama sheli" אתה הנשמה שלי Said to a female: "aht ha-neshama sheli" את הנשמה שלי
One who runs great risks or accepts great hardship for the sake of observing the religious laws of Judaism without actually sacrificing his or her life is also considered especially righteous. Such an act of figurative self-sacrifice is called mesirat nefesh (מסירת נפש, "giving over the soul").
Democritus meditating on the seat of the soul was created in 1868.
heart = lev (לב) soul = nefesh (× ×¤×©) heart and soul = lev venefesh (לב ×•× ×¤×©)