From the author Kinoko Nasu himself:
The Holy Grail War is unknown to the general population, but to what extent is it hidden from normal people? Are the Church people (supervisors) manipulating the media and police (or even the governmental level) to cover it up?
A: The Church manipulates information, while the Magic Association handles the media. Also, ...
actually the one posted by RNGesus.exe is the wrong one. while i have not seen the ufotable series, looking at the wikia on it you see it's Heroic Spirit EMIYA's chant as it's the one that ends with him saying "So as I pray".
since the question asks for Emiya Shirou, his is
I am the bone of my sword.
Steel is my body and fire is my blood.
I have created ...
Rules are made to be broken
This is the mantra to always keep in mind when engaging the Fate series.
By default—the "rule"—servants are summoned with their body as in their prime (physical prime normally, though servants renowned for more mental deeds would be in their mental prime, which could be quite a good deal older). Except when they aren't.