“As we crossed, she leaned over and said, ‘Persevere,’ ” Jackson told a packed audience at Chevalier Theatre in Medford last Thursday. “It was what I needed to hear to start me thinking about turning it around.” Listening to Jackson talk about her life and her memoir, “Lovely One,” I could not imagine how many times that stranger’s advice had strengthened her resolve — perhaps never more so than during her three years on the conservative-led high court. But what also struck me while listening to Jackson was her joy. This nation is struggling to live with the Trump administration’s...