Purple Rose Theatre premieres David MacGregor's play about Isaac Newton, "Gravity"

We all know about get-well cards, but in 1693, Sir Isaac Newton — the subject of David MacGregor’s world premiere play “Gravity” at Chelsea’s Purple Rose Theatre — wrote a letter to philosopher John Locke that was, well, kind of the opposite.

Michelle Mountain costars in "Gravity."

It read, “Being of the opinion that you have endeavored to embroil me with women and by other means I was so much affected with it as that when one told me you were sickly and would not live I answered that it was better if you were dead.”

So … that seems a bit harsh. But the unabashed nastiness of this letter was what first caught MacGregor’s attention.

“I didn’t know too much about Newton, but I caught part of a documentary about him while channel surfing at 2 in the morning,” MacGregor said. “I’d known about the apple falling on his head, and his work with the laws of motion, but this just seemed like such a bizarre thing for someone to say, so I decided to try and find out what prompted it.”

MacGregor set off on a research quest, reading books not only about Newton, but also about Locke and 18th century women.

“I got to a point where I had this big sheaf of notes, and I felt like a chef with the world’s most amazing ingredients,” said MacGregor. “But then I got scared, thinking that if I started down wrong path (with 'Gravity'), I wouldn’t be able to find my way back.”

Consequently, MacGregor let his research and idea for “Gravity” percolate for a while before writing the script.

Set in 1693 — the year Newton wrote the letter to Locke, as well as a similarly despairing (but less insulting) missive to diarist Sam Pepys — “Gravity” tells the story of Newton at a personal and professional crossroads.

“It’s an imagining of that time, when Newton was the age of 50,” said director Guy Sanville. “He suffered a nervous breakdown and was institutionalized. But then he got out, packed up his belongings, moved from Cambridge to London, bought a whole new wardrobe, had 20 portraits done of himself, and became warden of the Mint.”

Perhaps Newton (played by Alex Leydenfrost) was simply striving, in Oprah-speak, to “be his best self” — but the question nonetheless remains: What personal events brought on this huge life-shift?

“No one knew what he was doing,” said MacGregor. “There were all kinds of rumors and speculation. … He’d been working on something for years, and he’d published his landmark book (‘Principia Mathematica’) 6 years before then. … But he was working 18-20 hours a day, … and because he was a very paranoid person, he wouldn’t tell anyone about what he was working on. It all came to a head in that time in 1693.”

Newton’s real-life despised nemesis Robert Hooke appears as a character in the play, but he’s not the only one.

“This woman is introduced to him by his friend, and she actually understands his work,” said Sanville. “What more could a man want than a woman who understands his work?”

This mysterious patroness, played by Michelle Mountain, and Newton’s studies in alchemy, thus play a role in “Gravity,” as does Newton’s complex relationship with religion.

“He had clearly set himself the task of connecting to God in way no one else had,” said MacGregor, who noted that Newton’s father died before he was born, and his re-married mother left him with unloving relatives at age 3.

Because Newton’s earthly relationships had disappointed him, he put a great deal of stock in his relationship with God. But as MacGregor points out, this raises the stakes to the point of nearly being unbearable.

“What if he fails God, and God turns his back on him, too?” said MacGregor. “It’s a crucible situation, and it made sense to explore that.”

Jenn McKee is the entertainment digital journalist for AnnArbor.com. Reach her at jennmckee@annarbor.com or 734-623-2546, and follow her on Twitter @jennmckee.