The sequence of the primes is something of a mystery in number theory if not in all of mathematics. Hardly any topic has ever fascinated mathematicians more. Euler once said "e;Mathematicians have tried in vain to this day to discover some order in the sequence of prime numbers and we have reason to believe that it is a mystery into which the mind will never penetrate"e;. One key question has always been: Does there exist a single overarching organisational principle that accounts for why any prime follows another prime as the next largest prime in the prime sequence?A primary aim of this book is to show that such overarching and comprehensive principles do exist and govern the entire prime sequence. To unlock these secrets of harmony for the enthusiastic reader it is not necessary to dive too deep into mathematics but to unveil structures of organisation from different points of view. The Secret Harmony of Primes was written in 2012-2015 and represents a collection of the author's work in prime number theory throughout the last decades woven into a comprehensible storyline.