Even if you don't know a lot about Van Morrison, you probably know his song, “Brown-Eyed Girl.” But real fans of the Irish singer-songwriter know his best work came a year later, when he wrote the album “Astral Weeks” in Boston. Coming out the same year as hits such as the "White Album" from the Beatles, and the Jimi Hendrix Experience's "Electric Ladyland,” "Astral Weeks" soon became a cult classic.

Jim Braude was joined by author Ryan Walsh, whose new book "Astral Weeks: A Secret History of 1968," is full of untold stories about the underground worlds of 1968 Boston that influenced the man and his music.