I'm looking for a word or phrase for:
Something that is not only the perfect/archetypal/quintessential example of a concept, but also unequivocally validates the existence of the concept via its very existence.
Ex: Phineas Gage is [___] of medical miracles.
I could achieve this in two separate sentences ("Phineas Gage is the quintessential example of a medical miracle" and "Phineas Gage is unequivocal proof of the existence of medical miracles"), but I feel like there is a way authors communicate both via just one phrase.
I understand that these statements are redundant in the sense that saying "A is an example of B" is automatically proof of B, but I want to communicate the connotation more explicitly.
I think I'm close with the phrasing "ultimate testament to" but I would appreciate other suggestions.