Sondheim: Absolutely! That’s exactly what he taught me, when he criticized my poetic Hammerstein lyrics when I was starting out.13 He said, “That’s not what you feel. Don’t write what I feel. Write what you feel.” Oh! It had never occurred to me to write what I felt. And Oscar was the one who taught everyone to do that.

Write what you feel. Or as George’s muse, Dot, says to him in “Sunday,” “Anything you do,/Let it come from you./Then it will be new.”

And then for a moment you let in the depth and intensity and range of Stephen Sondheim’s feeling for the past half-century. That Tony and Maria of “West Side Story” first fell in love as Sondheim sharpened his Blackwing pencils, finding the words for their doomed romance at age 25. That Mrs. Lovett of “Sweeney Todd” hatched her diabolical plans from this writing couch as Sondheim talked to himself. That within Sondheim, somewhere, is both Georges Seurat and Fosca, Pseudolus and Mama Rose, John Wilkes Booth and Madame Armfeldt, Charley Kringas and Little Red Riding Hood. He has served up vodka stingers for Joanne (“Company”) and chrysanthemum tea for the Shogun (“Pacific Overtures”). Sixty years of iconic theatrical moments, and they exist as a result of the specific way Stephen Sondheim feels. Line by line, note by note, surprise by surprise.

And if you’re Sondheim, there are days like today, when you feel under the weather and the day is full of distractions. But there are also nights when you write “Finishing the Hat,” and you’re so proud of what you’ve made that you have to call a friend and say, “I just wrote this song.”

What’s important is that Sondheim is still here, staring down another deadline. Starting on a hat. Feeling his way toward the moment when time disappears.

Sondheim: You shouldn’t feel safe. You should feel, “I don’t know if I can write this.” That’s what I mean by dangerous, and I think that’s a good thing to do. Sacrifice something safe.

Variety, variety, variety, Mr. Sondheim. Don’t let up for a second. Surprise us.