All work and no play makes Jack a dull boy

I would like to know why It is the same for language.

It: All work and no play makes Jack a dull boy

There's an old saying in English: All work and no play makes Jack a dull boy. Or Jill. Psychologists tell us we need a balance between work and play to have a healthy lifestyle. And it is the same for language. One of the most noticeable features of work language is the technical vocabulary, or jargon, that people use. Outsiders won't understand it. A doctor might look at the face of someone who's had a fall and say to a colleague That's a nasty perorbital haematoma'. If you were the patient, and heard this remark, you might be worried. But basically all it means is you've got a black eye. Every profession has its jargon - law, banking, sport, physics, language teaching ... Thousands of specialised terms might be used. They add precision. And they also make people feel they belong together. You know you're a member of a group when you can comfortably talk shop. Jargon also saves time. That's why doctors say such things as BP and SOB (blood pressure, shortness of breath). It's quick and convenient. But they shouldn't use such terms to the patient. Work language and leisure language are two very different things. That's the argument of the Plain English Campaign, which wants specialists to speak clearly when talking to the public. It's easy for people to use jargon carelessly and annoy people. It's worse when it's used deliberately, to mislead the public. That's why we get so angry when we hear people using it to hide the truth. A politician once admitted that something he had said was “an instance of plausible deniability“. In other words, he'd told a lie!