Spoiler Musings of a Champion: The Power Source of the Timeless Sheikah Tech

[el :BeoWolf:]

I've always believed that Nayru is in fact the goddess of time.
One thing to notice is the Great Deku tree's story of how Hyrule was created. Nayru "poured her wisdom onto the earth and gave the spirit of law to the world"
This seems to imply that Nayru created the laws that govern the physics of the universe, such as time perhaps.

Nayru is also associated with the color blue, which is what timeshift stones and the ocarina of time are. They may even be the same material.
"With this talk of controlling time, one can't help but think of Ocarina of Time. The ocarina is the same color as the Timeshift Stones. Could they be made of the same material?"
"Its blue-white radiance brings to mind the Timeshift Stones found in the eras of antiquity." - Hyrule History pg. 53, 86

When Link pulls the master sword, he is enveloped by a blue light before traveling seven years in time.

Nayru the oracle is also associated with time along with the Harp of Ages.

 

[Fierce_Deity]

Well the Master Cycle Zero answers this, it's raw materials. I'm kidding of course.

 

[Oni Link 303]

I think the easiest way to answer this is to simply say that the Sheikah are the guardians and/or disciples of Hylia. Extrapolating on vague connections between the Timeshift Stones and the Sheikah is already dubious as is, given that "clear" Sheikah symbols, at large, remains mostly undistorted (with slight variations in design whilst keeping the same motif; a tear and three lashes) between games, even the Yiga keeps the same motif design. The symbol on the Timeshift Stones differs too much to say that there is a "definitive" connection without making a leap of logic.

Its more logical to think of it as the Sheikah being endowed with special powers, via, Hylia's blessing, as per Monk Oman Au's statement of "I am a humble monk blessed with the sight of Goddess Hylia" coincides with their status as "chosen guardians". Consider it as a parallel as to how A Link to the Past and Twilight Princess distinguishes the Hylians as the chosen race by the Golden Goddesses, and are granted special powers as a result.