The intermediate days of Pesah and Sukkot – the days of Hol HaMoed – are difficult to define. While not fully days of Yom Tov, neither are they regular days of the week. This necessitates establishing halakhic boundaries that will guide us in our activities on those days. As we will learn in this perek, the Sages work to find a system of laws that will clarify what types of activities are forbidden and which are permissible so that the holiness and uniqueness of Hol HaMoed can be kept. One of the ways of establishing these rules is by comparison to the halakhot that are found in parallel settings, for example, agricultural work that is forbidden or permitted during the Sabbatical year (shemitta).
The first Mishna in the massekhet discusses types of work that are not all that common in our day-and-age but which were basic to the needs of the farmer. When can fields be watered on Hol HaMoed or during the shemita year, times when agricultural work is generally forbidden, but activities that are done to sustain the field and to keep the produce from getting ruined would be permissible? The Mishna teaches that fields that cannot be sustained by rainfall and need to receive water from some type of irrigation, can be watered, so long as the method of watering is a fairly easy one. Thus, a plentiful water source like a well can be used, but rain water or mei kilon cannot.
Many explanations are offered for the term mei kilon that appears in the Mishna. The Aruk and the Ran suggest that a kilon is a deep ditch from which water will have to be collected by bucket to water the field. The Ri”f and the Ritva explain that the word kilon means a bucket, and is taken from the Aramaic kulta. Another approach suggests that kilon is a Greek word, which describes a method of raising water from a river or irrigation ditch by means of a long stick.