The 100 block of Court Street looks like a lot of places in Boston. There’s a bunch of tall buildings, a 7-Eleven, a bank, and a T stop nearby. It also happens to be just about the spot where in 1876, Alexander Graham Bell – and I say this without hyperbole – changed the course of human history.

"He was an extraordinary man. He was a genius," said Charlotte Gray, author of Reluctant Genius: "He was a, totally, you can either say an out of the box thinker or a total eccentric."

Born in Scotland, Bell moved to Canada with his parents after his two brothers died of tuberculosis and he also began showing signs that he, too, might succumb to the disease. Bell’s father was an elocution teacher and his fascination with the human voice was passed down to his son, who himself became a skilled teacher of the deaf.

"So he moved to Boston where there was an excellent school and where he could meet the kind of people he wanted to mingle with," explained Gray.

The kind of people Bell wanted to mingle with were folks who shared his interests outside the classroom: Electricity, magnetics, and the quest to transmit the human voice.  

"There were many scientists at this point – amateur and professional – working on what they were at that point calling the speaking telegraph," said Gray.

Bell himself was largely unschooled. But he was an intuitive thinker and an ingenious tinkerer. His day job offered him a unique understanding about not just how the human voice worked, but also how the ear received sound. This gave him a unique leg up on his contemporaries. And Bell had another distinct advantage over the others racing to invent the telephone: A city upon a hill.

"Boston was very important because in the late 19th century it was kind of the Silicon Valley of the United States," said Gray. "There were a lot of workshops where he could take drawings and get people with much better engineering skills than him to build prototypes."

Gray says Bell was no businessman and, crucially, it was in Massachusetts that he also found a keen investor: Gardener Hubbard, a Cambridge patent lawyer who was the father of one of his students.

Mr. Hubbard. Gardener Hubbard. And he realized that his deaf daughter’s teacher was in fact someone who could make a fortune for him.

In February 1876, Bell was on the precipice of a breakthrough. But Hubbard was growing increasingly exasperated. As Bell fiddled to perfect his prototype, Hubbard presciently urged him to submit his design drawings to the US Patent Office.

"In the end Hubbard himself goes down and registers for the patent and this is crucial because he was the first to register; just minutes, in fact, before one of Bell's rivals," said Gray.

On March 7, 1876, Bell was awarded the US Patent for his telephone. Just three days later, he broke the future wide open. In his Court Street lab he spoke into his device. In a separate room, his assistant Thomas Watson, heard him clear as…well…a bell. And what did Bell say on the world’s first phone call? "Mr. Watson, come here. I want to see you."

Bell’s primacy – and his patent – were challenged vigorously in the courts for years by a number of inventors. Even today there are those who claim that Bell wasn’t really the first to get there or, worse, that he outright stole other’s ideas. Gray disagrees.

"There’s absolutely no evidence that Bell had cheated. I would stick with the Alexander Graham Bell authorship of this invention," she said.

What is not disputed is that Bell’s telephone had an immediate and lasting impact. It was one of the most important inventions of his – or any other -- time.  

"The telephone was an entirely democratic invention because it affected every single persons lives, bringing people a sense that this was an interconnected world," said Gray.