Speiser of the University of Pennsylvania in the mid 20th century wrote that the word “Torah” () is based on a verbal stem signifying “to teach, guide,” and the like, and the derived noun can carry a variety of meanings, including in 54, and 57, specific rituals for what is sometimes called leprosy. Speiser argued that in context, the word cannot be mistaken for the title of the Pentateuch as a whole. Professor Jacob Milgrom, formerly of the University of California, Berkeley, noted that reddish substances, surrogates for blood, were among the ingredients of the purificatory rites for scale-diseased and corpse-contaminated persons, symbolizing the victory of the forces of life over death. Leviticus chapter 15 Dr. Elaine Goodfriend of California State University, Northridge, argued that the regulations of menstruation in probably had a smaller practical impact on women in ancient Israel than one might imagine, as women at that time probably menstruated less frequently than modern women due to sparser diet, more-frequent pregnancies, and longer breast-feeding (typically three years), all of which would have reduced their number of menstrual cycles. Professor Shaye Cohen of Harvard University noted that the only element in common between the “ritual” or physical impurities of and the “dangerous” or sinful impurities of is intercourse with a menstruant. Commandments According to the Sefer ha-Chinuch, there are 11 positive and no negative commandments in the parashah: To carry out the prescribed rules for purifying the person affected by skin disease (, tzara'at) The person affected by skin disease (, tzara'at) must shave off all his hair prior to purification. Every impure person must immerse in a mikveh to become pure. A person affected by skin disease (, tzara'at) must bring an offering after going to the mikveh. To observe the laws of impurity caused by a house's , tzara'at To observe the laws of impurity caused by a man's running issue A man who had a running issue must bring an offering after he goes to the mikveh. To observe the laws of impurity of a seminal emission To observe the laws of menstrual impurity To observe the laws of impurity caused by a woman's running issue A woman who had a running issue must bring an offering after she goes to the mikveh. In the liturgy Some Jews refer to the guilt offerings for skin disease in as part of readings on the offerings after the