principi (accent on the second 'i') , is the plural of 'principio' and is better spelled as 'principii' 'principio' has two main meanings: m1) the beginning of something m2a) a moral conviction (as in your context) or a moral guidance m2b) foundation of some knowledge; meaning m2b has a notable usage in the title: Philosophiae Naturalis Principia Mathematica, Latin for "Mathematical Principles of Natural Philosophy", a book written by Sir Isaac Newton, where the author stated his discoveries about gravitational laws, so founding the science of celestial mechanics in modern terms. principi (accent on the first 'i') is theplural of 'principe' (Eng.: prince)

Principi evangelici ! I principi ....indicates the bases and the initial assumptions on is based a theory , taking by convention or recognized by the right.