According to Jewish law, in order for business transactions to be valid, we must be certain that both parties understand the ramifications of their actions. Thus, someone who is in the halakhic category of a shoteh – a fool – cannot engage in buying and selling, and any transactions in which he participates will be nullified by the beit din.
In our Gemara, Rav Nahman introduces us to the case of bar Shatya. Here, bar does not mean “the son of,” but rather it is like bar mitzva, which means someone who is defined by a certain attribute – “a person obligated in mitzvot.” Similarly, bar Shatya is a person who is known to be mad. This bar Shatya entered into a business agreement to sell his land. What happens in a case where two witnesses testify that he sold the land while he was in full control of his faculties, while two other witnesses say that at the time of the sale he was crazy? The conclusion is that when such a person has a long-standing claim on the land that was sold, we see the conflicting testimonies as canceling each other out, and we determine that the land must be left status quo – in the possession of bar Shatya.
Various psychological maladies – particularly manic-depression – are oftentimes cyclical in nature, where the patient is fully rational for a length of time, yet at other times his ability to function in a cogent manner or make intelligent judgments and decisions is totally lacking. In such cases, the change from one state to another is sometimes gradual, which can lead to situations where it is difficult to determine whether he acted during one of his lucid moments or during his confused periods.
The Ritva explains that this discussion works with the assumption that as far as the halakha is concerned, such a person is considered to be fully sane when he is healthy and totally incompetent when he is stricken. The obligation of the court is to determine – to the best of its ability – what the situation was at the time of the transaction.