“welcome to this lecture. i am professor bergman, and i can imagine that you are wondering why a professor in history are doing in a lecture for students of the noble art of mathematics…”

the professor paused and looked out over his audience, a lecture hall full of students, more than he had expected to show up.

“…i assure you that i will not bore you with endless rambling of years and historic events… no i am here to entertain you with a story… a story i’ve published in a book, and also a story that greatly intrigues my grandson. this pleases and old man’s heart, and i hope that some day, he might finish the work i’ve started but have not yet been able to complete. and today i will extend that invitation to all of you…”

he gazed over the edges of his glasses and was fascinated by the attention his audience paid him.

“but before we dive deep into the content of my book, the lost gold, which i guess is why you all are here today to find, i will give a little historical perspective on the things i am about to talk to you about.”

he pushed a button on the remote he had in his hand and a large face became visible on big screen behind him.

“does anyone know who this could have been?”

“caesar!” someone from the crowd yelled.

“correct! five points to ravenclaw!”

there was a laughter in the crowd.

“julius caesar. emperor of the ancient roman empire. he excelled in many fields, as a politician, as a contributer on the literal and philosophical arena, as well as reforming the already strong and influential roman society. but today i bring him befor you for his military expertise. as a strong military leader with many strategic and expansive victories at hand, he also understood the importance of communication, and secret communication. the transaction of information was vital for his various endeavors. and even if i personally do not believe it was his creation, he played a significant part in the wide use of one of the first substitution encryptions the world has seen. it is even named after him. the caesar cipher. by today’s standards, a very simple encryption of information, but back then, like next gen tech from a secret government facility.”

he paused a moment to let what he just said sink in, and then he clicked the remote again to bring up the next image.

“since you are students of mathematics, i assume you are familiar with the substitution cipher rot13. can anyone tell me what secret lay hidden here?” he clicked the button again and a few letters appeared on the screen.

gbjryqnl