"What to do and what not to do" - two main questions of ethics. "Entertain a little and change a little" are the two main goals of this book. Alexander Silaev looks at the modern model of the world from an ethical point of view. Tells how to separate the right desires from the wrong ones, the latter - to put them on the wrong shelves. Analyzes failures from a mathematical point of view and bad advice. Offers to practice ethical questions and honestly answer some of them: how much will you betray a friend for? what border will you reach? can you sacrifice one person if the lives of five are at stake?