At the beginning of the project, Apple's design team settled on a plastic touch screen to cover the display. They figured that people will drop their phones all the time. Glass breaks; and we don't want a fragile device. Plastic was, at the time, the near-universal standard. It was an easy decision.

The first iPhone was debuted and teased several months before it's official release. For months, it sat behind glass enclosures as hype continued to build.

Tech reviewers, journalists and experts started to ask specific questions about the product, including the screen. They seemed somewhat dubious or disappointed with the prospect of a plastic touch screen.

Whilst all this was going on, test models were coming back with scratched screens. This confirmed that plastic screens are more susceptible to scratching than glass screens. Whilst this wasn't exactly a shock for the design team, CEO Steve Jobs saw it differently.

Jobs shifted his perspective - from the utility of the product, to how the customer would feel about the product.

If the phone goes in people's pockets with coins and keys (i.e. normal use), it will get at least a little scratched. If we designed the product, we chose to use a plastic screen. If the device comes out scratched as a result of our design, then it's our mistake. With glass however, if the customer goes out, drops their phone and it cracks, it's their fault. Customers are less likely to complain or be dissatisfied with the product because they were part of the failure.

Plastic will scratch. Glass can break.

A heavily scratched plastic screen will be perceived as poor quality and a shortcoming in design. A cracked glass screen is a user error, so it doesn’t raise questions on the quality of the product.

Better to make the customer feel partially responsible for the limitations of the product. 

It's true, right? You see someone using a phone with a cracked screen, and you assume that they dropped it because they're clumsy or careless. Now imagine that you splashed out on a premium product, which you treated with respect and care. If after some time it's covered in scratches, you would question the quality and design.

Jobs' uncanny ability to put himself in the shoes of consumers long before anyone else enabled him to build products and market them methodically in order to make people feel a certain way about the brand.

He then had to sell his vision and the reasoning behind it to the design team and manufacturers - somehow convincing them that switching from a plastic touch screen to a glass touch screen was so vital to the iPhone's success, that it had to be done, just three months before the official launch.

With the team on board, Apple, along with their manufacturers, were able to pull of a last-minute transition.

15 years on, the original iPhone is still regarded as the biggest, most influential, most successful tech product launch of all time - blowing it's competition out the water and setting the world of tech on a new trajectory.

Exactly how much of the iPhone's success can be attributed to the original version having a glass touch screen is impossible to quantify. It's one of a myriad of features; of human decisions; which would eventually make Apple the first trillion dollar company, and put a smartphone into the pockets of over 5 billion people.

Imagine having the courage and conviction to make that last-minute change, but also the foresight to understand how customers would feel about the product. Then, to single-handedly persuade the entire team to adopt and execute on the same vision...

Quite incredible.