The quotes are from Heinlein's "The Notebooks of Lazarus Long" which were sections in Time Enough for Love. In theory, they're the wisdom of a man who's thousands of years old. If you pay attention to the details, it turns out that they're selections by a computer (admittedly, a sentient computer) from hours of talk in which Lazarus Long was encouraged to say whatever he wanted. He could be mistaken or lying. He's none too pleased to be kept alive for his wisdom when he'd intended to commit suicide.

He may or may not be a mouthpiece for Heinlein.