as a square board. All of the halakhot of planting various species were stated with regard to a square-shaped garden bed. By inference: When it is like a square board, it is permitted; and when that is not the case, it is prohibited. Planting different species in horizontal and vertical rows without a space between the species is ineffective, even with circles. Rav Ashi replied: When the baraita says a square board, it does not mean that the only way to demarcate between different species is when the rows are in that configuration. Rather, it is to introduce a different leniency. The baraita came to permit a triangular plot that protrudes from it into another field. This means that a triangular protrusion into another field is considered a conspicuous demarcation only if the bed was square; in that case, no additional measures are necessary.

MISHNA: The mishna continues to cite a series of unrelated halakhot based upon biblical allusions. From where is it derived that a woman who discharges semen even on the third day after relations is ritually impure, just like one who touches semen (see Leviticus 15:17)? Because the semen remains fit for insemination, it can transmit impurity, as it is stated prior to the revelation at Sinai: ''And he said to the people, prepare yourselves for three days, do not approach a woman'' (Exodus 19:15). This three-day separation period ensured that even a woman who discharged semen would be pure. The mishna cites another halakha based on a biblical allusion: From where is it derived that one may wash the circumcision on the third day, meaning the third day after the circumcision, even if it occurs on Shabbat? As it is stated: ''And it came to pass on the third day when they were in pain'' (Genesis 34:25). The pain of circumcision lasts at least three days, and as long as the child is in pain he is considered to be in danger. The mishna cites another halakha with an allusion in the Bible: From where is it derived that one ties a scarlet strip of wool to the head of the scapegoat that is dispatched to Azazel? As it is stated: ''If your sins be like scarlet, they will become white like snow'' (Isaiah 1:18). Since the goat is offered to atone for sins, red wool is tied to its horns. The mishna cites another allusion. From where is it derived that smearing oil on one’s body is like drinking and is similarly prohibited on Yom Kippur? Although there is no proof for this, there is an allusion to it, as it is stated: ''And it comes into his inward parts like water and like oil into his bones'' (Psalms 109:18). The verse appears to equate smearing oil on one’s body with drinking water.

GEMARA: The Gemara comments on the halakhot cited in the mishna: The first clause in the mishna with regard to discharged semen is not in accordance with the opinion of Rabbi Elazar ben Azarya. The latter clause in the mishna with regard to circumcision is in accordance with the opinion of Rabbi Elazar ben Azarya. As, if one was to assert that the first clause is also in accordance with the opinion of Rabbi Elazar ben Azarya, we heard him say that in that case the woman is ritually pure. The Gemara explains: He who does not establish the mishna as reflecting the opinions of two tanna’im, has a variant reading of the mishna; he teaches the halakha in the first clause: The woman is ritually pure, and establishes the entire mishna in accordance with the opinion of Rabbi Elazar ben Azarya. And he who establishes the mishna as reflecting the opinions of two tanna’im, holds that the first clause is in accordance with the opinion of the Rabbis, and the latter clause is in accordance with the opinion of Rabbi Elazar ben Azarya.

The Gemara elaborates on the matter of a woman who discharges semen, citing that which the Sages taught in a baraita: A woman who discharges semen at any point on the third day is ritually pure; this is the statement of Rabbi Elazar ben Azarya. Rabbi Yishmael says: Even on the third day she is ritually impure. In addition, the only relevant tally is the number of days. The number of twelve-hour periods of night and day that passed is not relevant. Sometimes there are four twelve-hour periods that elapsed between cohabitation and discharge. If she had relations just before nightfall on Wednesday and discharged on Friday night at the beginning of Shabbat, it is considered as if three days passed, meaning Wednesday, Thursday and Friday; and four twelve-hour periods, meaning Wednesday night, Thursday day, Thursday night and Friday day. Sometimes there are five twelve-hour periods that elapsed, in a case where she discharged semen at the end of Friday night. Sometimes there are six twelve-hour periods that elapsed, if she had relations at the beginning of Tuesday night and discharged at the end of the third day. Rabbi Akiva says: The halakha is that it is always five twelve-hour periods. And if she had relations after part of the first period passed, she is given part of the sixth period to complete the requisite five twelve-hour periods, so that sixty hours will have elapsed between cohabitation and discharge.

The Rabbis said this before Rav Pappa, and some say that Rav Pappa said this to Rava: Granted, Rabbi Elazar ben Azarya holds in accordance with the opinion of the Rabbis, who say with regard to the revelation at Sinai that Moses instituted separation between husbands and wives on the fifth day of the week. Since everyone agrees that the Torah was given on Shabbat, husbands and wives were separated for two days. And Rabbi Yishmael holds in accordance with the opinion of Rabbi Yosei, who said that Moses instituted separation on the fourth day of the week, meaning that husbands and wives were separated for three days. However, in accordance with whose opinion did Rabbi Akiva state his opinion? Ritual impurity, in this case, is not based on the passage of days but on the passage of twelve-hour periods, which do not correspond to either opinion mentioned with regard to the revelation at Sinai. The Gemara answers: Actually, Rabbi Akiva holds in accordance with the opinion of Rabbi Yosei. However, his understanding is based on that which Rav Adda bar Ahava said: Moses ascended Mount Sinai early in the morning, and he descended early in the morning and related to them the mitzva of separation.

The Gemara explains the source of this opinion: He ascended Mount Sinai early in the morning, as it is written: ''And Moses rose up early in the morning, and went up to Mount Sinai, as the Lord had commanded him'' (Exodus 34:4). And he descended the mountain early in the morning, as it is written: ''Go descend and you shall ascend together with Aaron'' (Exodus 19:24). The Torah juxtaposes descent to ascent to establish that just as Moses’ ascent was early in the morning, so too, his descent was early in the morning. Moses told the people to separate in the early morning so that there would be five complete periods of separation over the course of the three days.

The Gemara asks: Why did he need to tell them to separate during the morning hours? Didn’t Rav Huna say: The Jewish people are holy and do not have relations during the day? It was not necessary to command them until night. The Gemara replies: It was necessary to tell them in the morning, as Rava said: If it was a dark house, it is permitted to have relations during the day. And similarly, Rava said, and some say that Rav Pappa said: A Torah scholar obscures the light in the room with his cloak and is thereby permitted to have relations during the day. Therefore, it was necessary to command the people to separate even during the daytime hours.