When an animal is slaughtered, the very first blood, dam ha-nefesh– the life blood that flows as long as the pumping action of the heart continues – will be spilled. This blood is called dam ha-nefesh because it is the blood that keeps the animal alive and with its loss will bring about cessation of the activity of the heart and ultimately, death. Even after the animal has lost this blood, there is dam ha-tamtzit – draining blood – that was in the arteries and will continue to flow out of the animal due to capillary action after the animal is already dead, as well as dam ha-eivarin – blood remaining in the animal’s limbs.
One of the most severe restrictions on eating in Jewish law is the prohibition against the consumption of blood, which is repeated several times in the Torah.
– And whatsoever man there be of the house of Israel, or of the strangers that sojourn among them, that eateth any manner of blood, I will set My face against that soul that eateth blood, and will cut him off from among his people. (Vayikra 17:10)
– For as to the life of all flesh, the blood thereof is all one with the life thereof; therefore I said unto the children of Israel: Ye shall eat the blood of no manner of flesh; for the life of all flesh is the blood thereof; whosoever eateth it shall be cut off. (Vayikra 17:14)
– Only ye shall not eat the blood; thou shalt pour it out upon the earth as water. ( 12:16)
– Only be steadfast in not eating the blood; for the blood is the life; and thou shalt not eat the life with the flesh. ( 12:23)
On today’s daf (=page) Rava asks why the punishment of karet is mentioned in conjunction with the consumption of blood three times and why the prohibition in general is mentioned five times. (Rashi comments that the prohibition against the consumption of blood is mentioned no less than nine times in the Torah, but Rava is enquiring only about those passages that are not used by the Sages as a source for other halakhot.)
In response, the Gemara explains that these refer to different types of blood. The punishment of karet applies to the blood of sacrifices, to ordinary blood and to dam ha-tamtzit. Aside from these three, the Torah also prohibits dam kisuy (blood that was covered in fulfillment of the requirement to cover certain animals’ blood after slaughter) and dam ha-eivarin.