“He that lieth down with dogs shall rise up with fleas.”Benjamin Franklin · Almanahul sărmanului Richard · 1758 · Almanahul sărmanului Richard, 1758
You don't have to err yourself: standing next to error is enough.
Franklin is describing contamination by proximity: you need not be the one doing wrong, it is enough to stay close to someone who is. The dogs are not evil in themselves, but they carry fleas. The mechanism is reputation and influence — the environment you sink into clings to you, both in other people's eyes and in your own habits. Someone who does business with shady partners will be suspected too, even with clean books, and their habits slowly seep in.
Franklin does not merely say to avoid shady people. He says something subtler: contamination runs both ways. It is not only that their reputation rubs off on you; you also slowly absorb their standards without noticing. Someone who spends every day near a person who bends the truth will start treating small distortions as normal. Think of a colleague who is always late: after a while, your own lateness starts feeling acceptable. That is why the filter is not only about how others see you, but about who you become. The good news is that the mechanism works in reverse too: keeping close to honest people quietly raises your own line. The question for the next step: how do you detect this drift early, from the inside, when you are the one contaminated?
Why it matters Useful when vetting partners, hires, or social circles. It reminds you that filters you skip at the entrance get paid for at the exit.