No biographical details should be necessary here. That's been covered extensively elsewhere, in print and in video. (I'm not even bothering to link. If you're connected, you've seen it all.)
Ted Kennedy was the senator in my home state since before I was born. Think about that. The same man has held that seat for my entire life. But just holding a senate seat is not that difficult. The power of incumbency only grows with time. At some point, unless you do something really horrible like try to pass a bill mandating abortions for every woman due to give birth on a Tuesday, it's a lifetime position like the Supreme Court. But what you do with that position is what makes you.
Teddy was a bit of a goof in his younger days. Not a great student and prone to bad behavior. But, unlike some other children of privilege who were goofs in their younger days and went into politics based on their family name, he worked hard to become a legislator of the top order. And beyond that a fighter, a real and true fighter, for unabashedly liberal causes. When Reaganism was in vogue (and still is, among a certain subset of our brainwashed nation) he defended not just the word "liberal", which had become, and continues to be, a dirty word to some, but the ideals behind it. He was not ashamed to say that compassion meant more than just feeling for others but acting on their behalf. This was the "great work".
No one expected much of Ted. But he ended up being the most consequential of all the Kennedys (Eunice being a possible exception). Even after the scandals of Chappaquiddick and his nephew William Kennedy Smith, he proved that there are second (and third and fourth) acts in American lives. The totality of Ted Kennedy, even with his personal disgraces, was overwhelmingly a net positive. You can thank him if you have a disability, or are a woman, or a child, or care about civil rights, or if you just happen to have a body. His death may re-focus energy on passing some form of useful health care legislation.
In our corporate-controlled government, Ted's example will not be followed by many. But a true government of, by and for the people would be populated by a lot more Ted Kennedys and a lot fewer John Boehners and Mitch McConnells.
Goodbye, senator. And thank you. You will be sorely missed.