Neil Diamond hasn’t performed live in any capacity since 2018, when an unexpected Parkinson’s disease diagnosis forced the singer-songwriter to retire from touring life. Such a crisis, both psychological and physical, is the basis for Diamond’s new musical, A Beautiful Noise, where he spars with a therapist about how he can find fulfillment when he’s not getting a sonic high in front of thousands of adoring fans each night — a narrative that was inspired by his own therapy sessions over the past few years to figure out the next chapter of his life. (Hint: The musical is the next chapter.) That makes the following all the more wonderful: Diamond showed up to A Beautiful Noise’s opening night on December 4, commandeered a theater box, and sang the first verse of “Sweet Caroline†with the help of the cast and audience. You can practically hear the “ba ba baâ€s from this paragraph.