The Mishna on today’s daf teaches that there are five different colors of blood that indicate a menstrual flow and will render a woman to be a nidda. The first of these colors is red, which is defined by the Mishna as being the color of the blood of a wound. The Gemara attempts to clarify this explanation and several opinions are presented:
- Rav Yehuda quotes Shmuel as teaching that it is similar to the blood of a slaughtered ox
- Ulla suggests that it is like the blood of a wound inflicted on a live bird
- Ze’eiri quotes Rabbi Ḥanina as teaching that it is the color of the blood of a squashed head louse.
- Ami of Vardina cites Rabbi Abbahu as teaching that it is like the blood of the little finger of the hand that was wounded and healed and wounded again.
- Rav Naḥman suggests that it is the color of bleeding that takes place during blood-letting.
Most of the rishonim understand that there is no real argument between the Sages, rather each of them shares an example of a color with which he is familiar and can identify. The Rambam (Mishneh Torah, Hilkhot Issurei Bia 5:11) disagrees, and quotes only the opinion of Rav Naḥman. The Rambam may have been influenced by the continuation of the Gemara, which relates the following story:
Ameimar and Mar Zutra and Rav Ashi were sitting before a bloodletter, and when the first bloodletter’s horn was taken off Ameimar he saw it and said to the others, ‘The red color that we learned about in the mishna is like this blood.’ When the second one was taken off from him, he said to them, ‘This has a different shade.’
‘One like myself,’ observed Rav Ashi, ‘Who does not know the difference between the one and the other must not act as an examiner of blood.’
For many generations physicians believed that blood-letting was a powerfully helpful remedy, both as a cure and as a general preventative therapy that would keep a person healthy. During Talmudic times such treatments were commonplace, both for human beings and for animals. At various times, blood-letting was the accepted treatment for almost all ailments.
Today it is well-established that blood-letting is not effective for most diseases. The only remaining condition for which it is used is Polycythemia vera, a disease where the body produces too many red blood cells. Among the symptoms of this illness are bleeding gums, excessive bleeding from ordinary cuts and bruises and a reddish color of the skin.