Let us begin by citing the primary source in the Mishnah for the category of DHA. Please note the commentary insertions which address the aforementioned objectives:
Mishna Moed Katan 1:1 (translation credits to Artscroll Mishnah Series - ‘Yad Avraham’): We may water an irrigated field during Ch”H… (Commentary: Since an irrigated field is affected adversely as soon as the watering is halted, an irretrievable loss would result. However… a field that can subsist without irrigation may not be watered even though the field would be improved by watering it. Since failure to irrigate would result in no irretrievable tangible loss, but rather, in loss of future profit, irrigation is forbidden.) However, we may not water irrigated fields, neither with rain water, nor with water from a cistern; nor may we dig ditches around grapevines (Commentary: … because they involve, or can lead to, excessive exertion).
DHA Summary: In this mishnah, we learn the following two points about DHA:
1) DHA is defined as being the irretrievable loss of current possession. It does not include future profit that will be forfeited. (We will expand on this crucial distinction below.)
2) The grounds of permissibility of ‘davar ha-aveid’ is limited by the factor of ‘tircha yeseira’ (excessive exertion) - i.e. if excessive exertion is involved, the work may not be done even for a DHA. “Regular” ‘tircha’, however is permissible.
Review and application
As we have done in the past, we will now turn to the contemporary sefer Hilchos Chol Hamoed Zichron Shlomo, by Rabbis Zucker and Francis, p. 67-79, for a review of this topic and some very valuable applications:
- Defining DHA
“DHA refers to loss or damage of either money or possessions, which will occur during or after the festival. Melacha may be done on Ch”H to prevent a loss of this type if the necessary measures cannot wait until after the festival… In the event of a substantial loss, even skilled work is permitted…”
- Distingushing between DHA and ‘menias ha-revach’ (loss of potential profit) “The loss must involve a loss of ‘keren’/principal in one’s possession, as opposed to ‘menias ha-revach’/loss of potential profit. …For example, the risk of losing one’s job by not working on Ch”H is a DHA, since something already in his possession will be lost – namely, his source of income. If, however, by failing to work, one faces only the loss of wages for the days of Ch”H, this is simply a loss of new profit and melacha is forbidden. There may be mitigating circumstances less severe than the loss of a job which would make working on Ch”H permissible, e.g. one’s employer will form an unfavorable impression of him or friction will arise between him and his co-workers. …The same holds true for a factory owner: If by closing his business he will merely forfeit new profit and not past earnings or capital, he may not open on Ch”H. If when closed, however, the owner will have to pay his workers their usual salaries, this is considered by many authorities to be a DHA. …Many authorities maintain that the loss of regular customers by a business constitutes a DHA… In practice, however, since many complex factors are involved, including the possibility of ‘zilzul ha-moed’/degradation of the festival, a factory owner or business-man should not conduct his business on Ch”H without first consulting a competent halachic authority. …In making a determination, the nature of the job must be considered, and whether it involves actual melacha. No decision should be made without consulting a Rav.”
- 4 possible limitations on the permissibility of DHA
a) ‘Tircha yeseira’/excessive exertion: …One may water garden plants with a hose or sprinkler system to prevent them from deteriorating. One may not, however, draw buckets of water and then carry them to the yard to water the plants…
b) ‘Mechavein melachto l’moed’/deliberate scheduling: The work may not be specifically planned for Ch”H.
c) ‘B’tzina’/in private: The work should, whenever possible, be done privately rather than in public view.
d) ‘Ma’aseh uman’/skilled labor is permitted to prevent a DHA only when a substantial loss is anticipated. When no more than a minimal loss is foreseen, however, only a ‘ma’aseh hedyot’ is permitted.
- Other forms of DHA
“DHA usually refers to the loss of something tangible. There are cases which differ somewhat from this prototype of DHA, but which may, nevertheless, be classified as such. For example, the loss of Torah knowledge is deemed a DHA. (!) For this reason, one who arrives at a new Torah insight may write it down, in order not to forget it! … The deprivation of an essential human need and the loss of certain rare opportunities are other instances of DHA. For example, if a person’s house was burglarized (chas v’shalom) on Ch”H and his entire wardrobe stolen, he may buy a new suit and have the necessary alterations made… even skilled melacha is permitted.”
- ‘Poeil she-ein lo mah yochal’/A poor laborer who lacks food to eat “A poor laborer is permitted to work on Ch”H to feed himself and his family, even if the job entails a ma’aseh uman. Anyone may employ this poor laborer even if the employer does not need the melacha done for the festival or to prevent a loss (i.e. because the employer is preventing the loss of the laborer’s impoverishment!)”
One final note which governs hilchos Ch”H:
“In general, one may not instruct a non-Jew to do any melacha for a Jew on Ch”H (with or without pay) which the Jew himself is forbidden to do. …An exception to the above is the case in which melacha is needed on Ch”H in order to fulfill a mitzvah….”