Leo Tolstoy 
Father Sergius [EPUB ebook] 

In Petersburg in the eighteen-forties a surprising event occurred. An officer of the Cuirassier Life Guards, a handsome prince who everyone predicted would become aide-de-camp to the Emperor Nicholas I. and have a brilliant career, left the service, broke off his engagement to a beautiful maid of honour, a favourite of the Empress’s, gave his small estate to his sister, and retired to a monastery to become a monk.
This event appeared extraordinary and inexplicable to those who did not know his inner motives, but for Prince Stepan Kasatsky himself it all occurred so naturally that he could not imagine how he could have acted otherwise.