The September 30 issue of TIME will profile Page and his decision to launch Calico. From the magazine’s preview article:

“Based in the Bay Area, not far from Google’s headquarters, Calico will be making longer-term bets than most health care firms. “In some industries, it takes ten or 20 years to go from an idea to something being real. Healthcare is certainly one of those areas,” said Page. “Maybe we should shoot for the things that are really, really important so ten or 20 years from now we have those things done.”

[…]

Google is keeping its exact plans close to the vest. But it is likely to use its data-processing might to shed new light on age-related maladies. Sources close to the project suggest Calico will start with a small number of employees and focus initially on researching new technology.

That approach may yield unlikely conclusions. “Are people really focused on the right things? One of the things I thought was amazing is that if you solve cancer, you’d add about three years to people’s average life expectancy,” Page said. “We think of solving cancer as this huge thing that’ll totally change the world. But when you really take a step back and look at it, yeah, there are many, many tragic cases of cancer, and it’s very, very sad, but in the aggregate, it’s not as big an advance as you might think.”

Ref: Google wants you to live forever – io9
Ref: Google to fight aging with new health startup Calico – Singularity Hub