Monday, March 29, 2010

Bedikat chametz

The mitzvah of checking for chametz occurs on the evening before Pesach. I can't find the source now (erev Pesach and I'm in a hurry), but my recollection is that the reason for checking at night by candlelight, rather than during the day, is that it is easier to find chametz at night than during the day.

This seems totally counterintuitive. Obviously, you would think, you can see better during the day so checking should be done then. Isn't it totally backwards to think you could see better at night?

I think the reasoning goes as follows. Nowadays we have two things that ancient people did not: modern building techniques and electricity. Once upon a time most people lived in closely spaced stone huts with small if any windows. Thus, most of their indoor areas were necessarily rather dark. Without electricity, the only way of lighting these areas was with candles.

So checking for chametz by candlelight made perfect sense: it meant using the most efficient possible indoor lighting. But why at nighttime? If most indoor areas received little light from outside, daylight would do little to help the checking. But it would interfere with checking, for the following reason. People's eyesight adjusts to the amount of light they perceive, and even a person who did bedikat chametz inside would probably go outside the building every so often. Upon reentering the home, everything would appear dark even with the available indoor lighting. But at night, it would be just as dark outside as inside. People could check the corners of their houses in the most effective way – with all the available indoor lighting (candles), and with the sensitivity in vision that was unavailable during the day.

Thursday, March 25, 2010


This is why I voted for Hillary Clinton in the primary, and McCain in the general election.

That's despite the fact that I support most of his domestic policies, including the recently passed health care bill.

Sunday, March 14, 2010

Brit Milah and reproduction

(Disclaimer: For a blog that supposedly represents the “beis”, this blog contains very frequent references to sex. It is tempting to ascribe this to the fact that I'm a single male, and thus think about these things all the time (Kiddushin 29b). But I prefer to ascribe this to the fact that sex, in the right circumstances, is an unavoidably important part of life. Most of the stories in Tanach are about sex or death, because those situations bring out the strongest emotions and present us with the hardest moral choices. It is natural, then, that many of the divrei Torah worth writing about should involve sex as well. The topic must of course be addressed with sufficient decency and reserve, but I try to do that, and hopefully I succeed.)

“I am El Shaddai: walk before me and be wholesome. I shall place my covenant between me and you, and I will make you very very numerous. As for me, behold my covenant is with you, and you shall be the father of many nations. Your name shall no longer be called Avram; your name shall be Avraham, for I have made you the father of many nations. I shall make you very very fruitful, and make you into peoples, and kings will descend from you. I shall uphold my covenant between me and you and your offspring forever after you, as an eternal covenant – to be God to you and your offspring after you. I shall give you and your offspring after you the land of your dwelling, all the land of Canaan, as an eternal inheritance, and I shall be their God.” (Breishit 17:1-8)

In these verses, the introduction to the covenant of “brit milah” which God makes with Avraham, the main focus is on offspring – how many there will be and how many nations they will become. To make this more concrete, the birth of Yitzchak (the first such offspring) is foretold. Later on, it is stated that the punishment for breaking the covenant (by not being circumcised) is “karet” - being “cut off” from your people. According to one prominent explanation, this means the end of one's family tree due to lack of descendants. If so, this is a fitting punishment, the exact reversal of the reward of having many descendants.

Why is circumcision the sign of this covenant? The obvious answer is that circumcision involves the sexual organ, and thus represents the covenant's focus on reproduction. But this answer is insufficient. Surely there are other, less violent, ways of symbolizing reproduction. Why must the symbolism be achieved by cutting off part of the body, even a useless part?

Perhaps the following comparison will help illustrate why. Circumcision consists of the removal of a piece of skin or a membrane from the surface of the male genitals. Women, too, possess a membrane on the surface of their genitals. It too is removed at some point in their lives, stereotypically, when they begin married life. The removal is a necessary condition for them to become pregnant and have children. Perhaps male circumcision is meant to parallel this change in the woman's body. Just as the woman's genitals must be exposed before a couple can have offspring, so too the man's genitals be exposed.

Of course, there is a difference between the modifications. Rupture of the hymen is a natural process, and is a physical prerequisite for pregnancy and birth. Circumcision, in contrast, does not benefit for the reproductive process (on the contrary, it somewhat resembles castration, which prevents reproduction). But for a believing Jew circumcision is equally a prerequisite to birth, since in return for it God rewards us with offspring. The foreskin is a spiritual “impediment” to birth, just like the physical impediment in the woman's body. Removing both “impediments” demonstrates our faith in God's control of the world: that it is run by reward and punishment, not only by deterministic natural processes.

Midrash Tanhuma (Tazria) tells the story of a Roman who asked Rabbi Akiva whether circumcision did not contradict the idea that things made by God are perfect, and thus in no need of human improvement. R' Akiva replied with the example of bread: a loaf of bread is surely superior to wheat kernels, but God only made the kernels, and left us to finish the job by grinding flour and baking bread. Similarly, God made the human body, but left the final job of perfecting the body to us.

The midrash speaks of the male body, but its message applies equally to the female body. When human beings have children, we participate in creation just as God originally did. This is one of the most significant and Godly moments of our lives. As the Torah views it, both male and female bodies need perfecting before this can occur.

Sunday, March 07, 2010

Thoughts on Ki Tisa

[God] gave to Moses, when He had finished speaking with him on mount Sinai, the two tablets of the testimony, tablets of stone, written with the finger of God. (31:18)

What is the point of the tablets? Israel had already heard the Ten Commandments as well as all the mitzvot in parshat Mishpatim. What is the point in getting the Ten Commandments again, this time in written form?

I think that the answer is that written tablets signify a more serious and formal commitment than the verbal statements (19:5, 19:8, 24:3, 24:7) that God and Israel had previously made to each other. It is often said that Sinai was like a marriage between Israel and God. More precisely, we can say that the verbal statements were like an engagement, and the actions that followed like a marriage. In halachic terminology, the tablets were a “shtar kidushin” (and the two keruvim hovering over them in the Mishkan, like “edei kidushin”). When Moshe took the tablets to Israel, he was effectively delivering the marriage document (or, in modern terms, the wedding ring) to the Jewish people. Once it was delivered, the marriage would be formalized.

The Mishkan, whose description dominates Sefer Shemot after the giving of the Torah, is the “home” in which God and Israel would dwell after their marriage. God's command in parshat Terumah begins by saying “They shall make me a mikdash, and I shall dwell among them.” (25:8) R' Yaakov Medan shows that the word “mikdash” technically refers to the tablets, not to the sanctuary as a whole. Thus, God's dwelling among us is a result of our possession of the tablets. Once we receive the “wedding ring”, we can then move into our shared home with God.

At that very moment when Moshe came down with the tablets, Israel chose to betray God by worshiping the Golden Calf. The midrash (Shabbat 88b) likens this to a bride who cheats on her husband(-to-be?) while under the chuppah. This midrash receives a much stronger basis when we consider the role of the tablets. Moshe broke the tablets upon realizing he could no longer bring them to the Jewish people. The “ring” could not be delivered while the bride was consorting with someone other than the groom. After forgiveness was obtained for the Golden Calf, a new “ring” had to be forged (the second tablets), and a brand new wedding ceremony performed.

[God] said: “You may not see my face, for a person may not see my face and live.” (33:20)

If we take this verse literally, we run into two problems: we do not want to say that God has a body (and face); and it's not clear why seeing such a face should entail death. But what basis do we have for taking it non-literally, and if we do take it non-literally, what exactly does it mean?

I think the answer comes from Vayikra 20:5: “And I shall put my face against that man (ושמתי את פני באיש ההוא) and his family, and I shall cut off him and all who stray after him, to stray after the Molech, from among their people.” There, having God's “face” opposite you means to be fully exposed to God and His intervention in the world.

Perhaps the same is true regarding Moshe here. A major theme of the Golden Calf episode is that Israel had to be separated somewhat from God, because otherwise Israel's occasional sins would lead to punishments that Israel could not bear. “You are a stiff-necked people; if for one moment I would go up in your midst, then I would [be forced to] destroy you.” (33:5) Something similar appears to happen here with Moshe himself. Even he could not survive the most extreme level of closeness to, and scrutiny by, God. Thus he was limited to seeing God's “backside” - that is to say, an encounter in which God was not “looking at” him, or scrutinizing his actions.

Here and elsewhere Moshe is said to speak to God “face to face”. We are forced to say that this encounter was less intense than “seeing” face to face. Perhaps “speaking” face to face simply means a normal dialog in which both sides can say what they want to say. (Since prophecy is often described in Tanach as a physically overwhelming trance-like experience, such a dialog by Moshe would be quite unusual and impressive). Meanwhile, “seeing” God means something much more intense. God is often physically represented in Tanach by something like a fire or tornado. To “be seen by” either of those, that is to sense their proximity to you, is physically dangerous, So is “being seen by” God.

[God said:] “...for I will not go up in the your midst; for you are a stiff-necked people; lest I consume you on the way.” When the people heard these evil tidings, they mourned; and no man put on his ornaments. Hashem said to Moshe: “Say to the children of Israel: You are a stiff-necked people; if I go up in your midst for one moment, I shall consume you. Therefore now take off your ornaments, that I may know what to do with you.” And the children of Israel stripped themselves of their ornaments from Mt. Horev onward. (33:4-6)

In these verses, there are three separate mentions of the Israelites' “ornaments”. They go as follows: (A) Israel does not put on their ornaments, (B) God tells them to take off their ornaments, (C) From then on Israel does not wear ornaments.

Part (B) is hard to understand. Why is God telling them to remove ornaments that have already been removed? Here are two possible, and complementary, answers.

1) As part of their mourning, Israel chose not to wear ornaments. But that was temporary: when the mourning ended, as it naturally would, they would resume wearing ornaments. God in effect commanded that they never again put on ornaments. The next verse tells us that they obeyed the command, and from then on ornaments were never worn.

2) Different words are used in each of the three mentions of ornaments. In (A), Israel does not put on (“lo shatu”) ornaments. In (B), God tells them to take off (“hored”) ornaments. In (C), Israel does not wear (“vayinatzlu”) ornaments. Perhaps, as part of the mourning, Israelites did not put on additional ornaments, but kept on the ones they were already wearing. God then told them to go a step further, to take off the ones they were currently wearing. From that point on, Israel neither put on nor kept wearing ornaments – they were entirely “stripped” of ornaments.

Why this distinction between putting on and keeping on ornaments? Perhaps, the reasons for not putting them on and not keeping them on are distinct. Mourning, presumably, means you should be indifferent to your appearance. Thus it's inappropriate to spend time beautifying yourself by putting on ornaments. But precisely because you are indifferent to your appearance, you do not bother to think about ornaments you're already wearing, so the fact that you're wearing them is not a problem. (This is even more true if, as is possible, the ornaments already being worn were part of normal and expected dress and had little “ornamental” value.) Thus, mourning is perfectly consistent with the Israelites' not taking off the ornaments they were already wearing.

When God told Israel to take off even those ornaments (or, according to the other explanation, keep all ornaments off permanently), He had a different purpose in mind. Remember that the Golden Calf was made from Israelite earrings (Shemot 32:3). Thus ornaments were potentially dangerous raw materials for idolatry. God told the people to stop wearing ornaments completely. Perhaps this reduced the risk that another Golden Calf would someday be made, and it certainly provided a constant reminder of the sin and a warning that it not be repeated.

Thus, God's command was not a reflection of mourning, but of distancing from idolatry. The people's not putting on ornaments was selfish in a way – a result of their distress at the recently announced punishment. Their removal of ornaments was selfless – a way of promoting moral behavior. God noticed their response to the punishment, and had them “tweak” it slightly. By this slight change, the people's actions were channeled in a more moral direction.

This moral improvement was held in their favor just a few days later. The people received forgiveness for the Golden Calf, not only because Moshe asked for it, but because the people began to deserve it. It is a sign of God's kindness and love for us that He initiated the very change that was later used as justification for our forgiveness.

One might think that by forgiving the people, God chose the path of mercy over strict justice. But in truth, there was no deficiency of justice in God's decision. Rather, the attribute of mercy was used to changed the situation, until the “merciful” conclusion became truly just.

Tuesday, March 02, 2010

On-time flights

As described here, many US airlines have been increasing the scheduled durations of their flights. The point is that a higher fraction of actual flights will arrive within the scheduled time, increasing the airline's "on-time" ratio and thus improving its standing with consumers. This is deceptive since, contrary to customers' expectations, on-time ratio changes while the flights themselves all take exactly the same time.

I think the best way to avoid this problem is to calculate on-time ratio in a different way. Flight time should not be compared to an arbitrary scheduled time. Rather, the FAA should take all flights between a given pair of airports in a year, and calculate the average physical time it took to fly between them (or, perhaps more usefully, the 75th percentile of flight times – the time that 75% of flights between these airports were faster than). If a given flight beats this average, it is considered "on-time". Thus, a totally objective on-time ratio can be developed.

Some tweaks may be needed to make such a formula fair, for example, comparing flights only to other flights with the same plane model or at the same time of day. But in an age when everyone and their sister are coming up with new sabermetric measurements, the difficulty of number crunching should not be an issue.