What is intelligence? Why does the speed of solving problems depend? Why can one person sit over a puzzle for a day, but never find the answer, while another finds it in a matter of seconds? We offer you a mini-textbook on intelligence development. After searching through it, you can quickly and effortlessly answer questions from numerous intellectual texts. By constantly training the "muscles" of intelligence, forcing the "intellectual muscles" to work with full dedication, you will easily find a solution in any life situations.