Is it possible to express beauty using formulas and equations?  Is there a single standard of beauty in the world?  Is it possible to measure harmony using a compass and a ruler?  Mathematics gives an affirmative answer to all these questions.  The golden ratio is the key to understanding the secrets of perfection in nature and art.  It is the observance of “divine proportion” that helps artists achieve an aesthetic ideal. The book “The Golden Ratio.  The Mathematical Language of Beauty" opens the series "The World of Mathematics" - a unique project that allows the reader to touch the secrets of this amazing science.