Our Gemara on Amud Beis discusses how various stains and substances on clothing cause a disqualification in the purification immersion because they act as a barrier between the water and the garment. While such an issue ought to be factual—i.e., does the water penetrate or not, or how much water must penetrate—instead, they are based on subjective human experience. Therefore, blood and fat stains are considered a barrier, but for a butcher who is used to blood stains, and a fat seller who is tolerant of fat stains, they are not disqualifying barriers. This is a fascinating and underrated aspect of Halacha: the extent to which personal subjectivity affects the ruling.

Then the Gemara goes one more step into the psychological and subjective world. What if a person who is both a fat seller and a butcher has both fat and blood stains? Do we say he cares about neither, or perhaps he reached a tipping point and cannot tolerate two kinds of stains, even if each alone is fine?

The discussion implies that it is a given that the butcher would not tolerate the fat seller’s fat stains, nor would the fat seller tolerate the butcher’s blood stains.

This is a more literal enactment of the aphorism that no one wants to pick up another person’s “pekaleh.” (Imagine everyone got a chance to dump their problems but could not walk out of the room without taking at least one package. According to the parable, after all is said and done, no one finds the other person’s burden attractive either, so in the end, they just pick up their own package and move on.)

All of this speaks to the idea that objective reality is not necessarily a real thing, and the world and life we live are much more determined by our subjective feelings and states.