[Avodah] Chazal's understanding of the brain and the heart

[M Cohen]

Recently there was a discussion on Areivim between
RNS and RYG wrt to Chazal's understanding of the brain and the heart
(as it affected definition of death)

of interest to this topic, the following was mentioned in the R Reisman
chumash shir...

Rav Yaakov Kamenetsky in Sefer Devarim on Pasuk 6:5 says a Chiddush. He says
it always disturbed him why there is no word for the brain in Tanach. Moach
in Tanach doesn't refer to the brain although it is used that way in modern
Hebrew. There is no word for the brain. 

Rav Yaakov is mechadeish that the word Leiv that refers to thought is really
a reference to the brain. Leiv is a reference to the emotional aspect of the
brain. The idea to serve Hashem with all your heart means with all your
intellect and with all your thought. So Rav Yaakov has this idea that Leiv
in Tanach is actually a reference not to heart and flesh but to the mind,
the emotional mind.

R Reisman writes that Rashi Shemos 4:14 seems to contradict that. Ra'ah
v'samach b'libo according to Rav Yaakov should mean, that he will rejoice
emotionally with his thoughts, in his mind. In the Zechus of that Aharon was
Zoche to the Choshen. 

The Choshen was not on his Leiv (brain) of thought, but on his chest near
the heart and therefore it is difficult to understand and it was in the
Zechus of v'samach b'libo. It would seem that the word Leiv is a reference
to the heart.