Lady Bird Johnson — a nickname she acquired as child growing up in Texas — is recounting the assassination of President John F. Kennedy. Her cadence is measured, her account riveting.

Both Lady Bird and the president were native Texans. He died in 1973. Sarah Hopwood, a nanny, visited the family garden on a recent day with four children ages 2 to 6.

The thing that strikes you first is her voice. Lady Bird Johnson recorded 123 hours of audio tapes recounting the ins and outs of her husband Lyndon Johnson’s administration.

Lady Bird Johnson embodied contradiction, cloaking her gravitas in Southern charm. Even her name made that clear. From infancy onward, Claudia Alta Taylor (born in 1912) was known to everyone as ...