I am currently studying the first order of the Mishnah, Zera'im ("seeds"), and wading through vast swathes of ancient agricultural laws - what may be harvested during the shemittah (Sabbatical) year, for example, and what qualifies as tithed produce - complicated by a range of botanical Hebrew vocabulary that never came up in ulpan.
However, last night I came across a rabbinic gem. If one vows to donate a certain portion of produce, and accidentally called it the wrong type of offering,
לא אמר כלום, עד שיהא פיו וליבו שווין.
Lo amar kelum, ad sheyehei piv velibo shavin.
He has not said anything valid until his mouth and heart are in agreement. (Terumot 3:8)
How often is it that our mouths and hearts are in true alignment? Don't we often say things that we do not mean, whether accidental or on purpose? Is it even possible to expect such harmony?
The Mishnah is pointing to a fundamental feature of the human psyche - that we are complicated, and that our words do not always reflect our intent, such that we cannot even necessarily assume the validity of the vows of another. Of course, we already know this about ourselves. To assume this of others, on occasion, may help us to understand better those around us.