Solon of Athens (c. 638 – c. 558 BC) is credited with three key inventions in the legal profession.
Around 505 BC the people of Athens came to him and said, "How do we know that the law really is what you say it is, and you're not just making it up as you go along?"
Solon replied, "I will have the laws engraved on large slabs of wood (called axones) and set up in the Prytaneum for all to read who can."
Thus he is credited with inventing the written code of laws.
This was a great help, but after a while Solon wanted to retire and travel the world, at least as far as sunny Egypt.
The people of Athens complained "If you go, who's going to help us figure out how those written laws apply?"
Solon replied, "Some of you must make it your work to read the law until you can apply it to any case."
Thus he is credited with inventing the profession of lawyer.
Solon enjoyed his retirement and travelling about.
Eventually, a delegation of lawyers from Athens caught up with him and complained "We are very unpopular, for when we lose a case our client is unhappy and when we win a case the other guy is. What should we do?"
Solon replied, "Well, I left town."
Thus he is credited with inventing the lawyer joke.