1:
After kiddush we proceed to the celebratory meal. Before eating, however, we must ritually wash our hands and break bread. The rules and regulations concerning washing the hands before a meal are set out in the Shulĥan Arukh in Oraĥ Ĥayyim 158 onwards, so it is to that place that we now turn our attention. A full explanation of the history, the etiology and the detailed laws of ritual purity can be found in Tractate Yadayyim. Here we shall confine ourselves to a brief synopsis - and only to that which is relevant to what happens in the home on Erev Shabbat.

2:
Whenever we eat bread we are required to wash our hands before doing so. This, like the lighting of candles before Shabbat, is a rabbinic command, not one that derives directly from the Torah. (For more details about such commands see Shabbat 016.) The reasons that lie behind the requirement that we wash our hands ritually before eating bread are threefold:

• Considerations of ritual purity;
  
• Considerations of holiness;
  
• Considerations of hygiene and cleanliness.

We shall now elaborate on each of these reasons, but let us first emphasize that the requirement is not that we just wash our hands (which would fulfill the third consideration mention above), but that we do so in a ritual manner. Someone who just washes their hands before eating bread has not fulfilled the mitzvah of netilat yadayyim - ritually washing their hands.

3:
In ancient times Israel's priesthood was sustained by donations made by the Israelite farmer to the priest or priests of his choice. This freed the priests from the necessity of earning a livelihood and permitted them to dedicate themselves entirely to the ritual of the Bet Mikdash as the agents of all Israel. The law - biblical and rabbinic - sets out certain donatives which must be separated off from produce and given to the priests before the rest of the produce might be eaten. (There were also donatives for the Levites, the destitute and for boosting the economy of Jerusalem, but they do not concern us here.) These donatives are called terumah in Hebrew. Over the years we have given a more detailed explanation of these donatives several times. Those interested might find Peah 044 informative, for example.

4:
The priests were required to be in a state of ritual purity before eating any produce that came their way as terumah. Since our hands get everywhere and can easily become ritually impure without our even being aware of it the sages legislated that the priests must ritually wash their hands before eating their terumah. (If they were ritually impure and touched the terumah they would pass on that ritual impurity by contagion and the food would be prohibited.) However, in order to ensure that the priests would perform netilat yadayyim before eating their terumah the sages enlarged the scope of their ruling and enacted that every Jew was required to perform netilat yadayyim before eating bread. (The produce which the priests received most regularly was, of course, grain that could be made into flour; so the form in which terumah was usually eaten was as bread.)

5:
The second reason which prompted the sages to introduce netilat yadayyim was philosophic. In the section of the Torah which deals with what we now call kashrut there is a summation [Leviticus 11:44]:

Eating food is not just an existential necessity: according to the sages it is a sacred duty. One can eat food like the animal which we are; but we can also elevate this necessity to the level of a sacred act which removes us from the level of the animal which just grazes or rips its prey to one of conscious humanity. By requiring us to ritually wash our hands before eating bread (the staple food) the sages are making us aware of the holiness of the act we are about to perform.

6:
The consideration of hygiene and cleanliness does not, I think, require any elaboration on my part.

To be continued.

In Shabbat 033 we learned that a glass of wine for kiddush ideally should contain at least one revi'it of wine and that one must drink from that cup at least a 'cheekful'. Zeev Orzech writes:

I assume that what we learned about the quantity of wine to be drunk at the Friday-night kiddush also holds for the kiddush at the seder table. Does it also hold for the rest of the arba kosot, or is the rule there: kezayit?

I respond:

The term arba kosot that Zeev uses refers to the four cups of wine that are obligatory during the Passover Seder service. The first of the four cups is that of kiddush and the others are spread out during the celebratory service. However, the reason for drinking these four cups of wine is different from the reason for drinking wine for kiddush. Each one of these four cups (including that of the kiddush) is drunk as an indication that we are free, independent and emancipated. Therefore, the minimal amount to be drunk for all four (including that of the kiddush) is not less that a complete revi'it: a mere 'cheekful' will not do. A revi'it is the equivalent of about 90 cc's; a kezayit is a measure of solids, not liquids, and therefore has no relevance to the amount of wine drunk at the Seder service.