Harry is given an ancient manual which describes a path to a power the Dark Lord knows not.
Harry nodded. He somehow could not find words to tell them what it meant to him, to see them all ranged there, on his side. Instead he smiled, raised a hand in farewell, turned around, and led the way out of the station toward the sunlit street, with Uncle Vernon, Aunt Petunia, and Dudley hurrying along in his wake.
Harry Potter and the Order of the Phoenix, by J.K. Rowling
"Harry, wait!" came a voice from behind him. When he turned around, he saw Ginny running towards him carrying some sort of parcel. Puzzled, Harry stopped and waited for her, ignoring the frustrated sigh his Uncle gave.
Ginny stopped in front of him and hesitated for a moment before she thrust the object in her hand, which Harry now saw was a slim book, towards him. "Here," she said in a slightly unsteady voice. She was looking down at her trainers.
Harry took the small book, which was bound in soft leather, and looked at the title. The Passion of the Warrior, by Godric Gryffindor. Not quite understanding, Harry looked back up at Ginny for an explanation.
Ginny finally stopped looking at her trainers and gazed straight into Harry's eyes. "It was your fathers," she said, as if it was no big deal. "Well, sort of. The original was his, but it was almost unreadable. I had to rewrite the whole thing. Sirius asked me to, even though I couldn't read it"
Harry opened the book to a random page and read a paragraph.
...some exceptions the true warrior should make is in the taking of a lover and in raising a family. All men should seek to sire children, so that life may persist on this earth, and they should of course seek to instill their children with their knowledge. One may think that this is the sole purpose a Warrior would have in taking a women into his bed, but this is not so. It cannot be denied that the softness of a woman's sweet breasts, or the warmth of resting between her gentle thighs will give the Warrior a taste of the peace he so longs for, and thus heals and rejuvenates him far more then the divers cures of the healers.
Blushing furiously, Harry tore his eyes from the pages and blurted out, "You couldn't read this?"
Ginny raised an eye brow questioningly at Harry. Perhaps she had noticed his blush. "No, I couldn't. Sirius said that it is spelled so only men of Potter blood can read it. I had to trace out each individual letter myself. I'm sorry that the original didn't survive. As soon as I had finished transcribing it, the original crumbled to dust. But it looks like all the enchantments went with whatever I wrote into the new book, because I couldn't read it either." She was still looking into Harry's eyes.
Harry swallowed the lump in his throat. Ginny had transcribed an entire book she couldn't even read for him. Harry had never done anything for her before. When he said as much, Ginny snorted.
"Other then saving my life you mean?"
Harry opened his mouth, about to reply something along the lines of "It was nothing" we he abruptly shut his mouth. Somehow he thought that was the wrong thing to say. Before he could think of something else, he heard a growl from behind him.
"Hurry up, boy! We've wasted enough time on you-"
"Shut up!" Harry hissed at him, which actually froze his Uncle in his tracks. Giving his Uncle a stony glare for a moment, and just a bit surprised when his Uncle nodded meekly while his Aunt and cousin both tried to hide behind his massive girth, Harry eventually turned his attention back to Ginny. Seeing her standing patiently, Harry felt his face soften. "Thank you," Harry said, softly, simply, and sincerely.
Ginny's face broke into a radiant smile, which stunned Harry for a moment, before she stood up on the tips of her toes and rested her hands on his shoulders so that she could press a small kiss to his cheek. Before she pulled away, she placed her lips near his ear and whispered gently, "Your welcome. Stay safe, Harry."
She smiled again, turned around and was gone, leaving Harry quite confused.
It wasn't until Harry was alone in his room later that night that Harry opened the book again. He definitely did not want to read a thousand year old sex manual while riding in the car with his relatives. When he opened the book and began to read at the beginning, he quickly realized that his earlier assumption about the book was wrong.
Many have wondered at the source of my mastery over the magical arts, most especially those who knew also my three companions, Helga, Rowena, and Salazar. It is quite obvious to all those who new us that Salazar was by far my superior in the subtle intricacies of magic, Rowena's knowledge dwarfed mine, and Helga has ever been the most perceptive and wise of our small company. Why then, have I always been renown as the most powerful of us four? Why have I the most feared reputation in battle? It is because I have learned of a way of harnessing my magic without resort to arcane gestures and incantations, nor precise arithmantic formulae, not even an understanding of the force inherent in all things of nature. I have aligned my mind, body, and soul, and forged them all into a mighty sword. I then enflamed this sword with passionate purpose...
Harry was instantly engrossed. The writing seemed to him to have an almost poetic measure to them, and unlike most texts on magic that he has come across, Harry found he had no trouble grasping the meaning behind the words.
...order to achieve this state, the Warrior must constantly thrust himself past the point of all endurance. The power in our Hearts can only be discovered when it is beating so furiously that it seems ready to burst from our chest, and when our limbs are close to being given over to palsy. When our vision begins to fade from exhaustion, and our ears ring from the exertion, our mind may be put to rest. Then- when our mind is perfectly still but our body is wracked with fury, our soul will burst forth and fill our entire being. Only then will a Warrior see the world as he was meant to see it.
The book was not particularly long, consisting of only a few score pages. It continued to explain the methods for achieving the state which the founder called "Enflaming thyself with Passion." It also outlined a code for daily living, which was what the paragraph he had read at the train station was talking about. It basically explained the a Warrior who would master this method must devote himself fully to discipling his entire self and craft it into a sort of weapon. It did a slightly less satisfactory job of explaining that a Warrior could have a life outside of war, but it should be virtuous-such as having a family- and apparently, having sex with women.
Harry also found that he was feeling something he hadn't felt since he saw Sirius fall through the veil, or since the night when Dumbledore laid out his destiny before him. Harry knew that Voldemort was far more Knowledgeable that Harry would ever be. He was also far more skilled at "the intricacies" of magic then Harry was. Here was a way for Harry to fight back. It seemed that Godric Gryffindor had reached down through the centuries and armed a Warrior with a way to defeat the descendant of his own foe, Salazar Slytherin. Harry wouldn't squander this gift. He had lost his parents when he was but a child, and now he had lost the man that his parents had wanted to care for him. Beginning at this very moment, Harry would align his mind, body, and soul, forge all three into a mighty sword-then enflame himself with a passionate purpose.