In 2004, pianist, composer and musicologist R.K. Owens wrote a set of three piano pieces, titled 'Lonely Pilgrimage'. Fifteen years later, R.K. Owens measured the bar length of the first movement, 'Flowers in the Rain', and realised that the climactic moment of the piece of music occurred at the exact point of the Golden Ratio. Subconsciously, the composition was written using the mathematics of the Golden Ratio, Fibonacci Sequence, Vesica Piscis and Pi, the mathematics of Sacred Geometry. The same proportions within the piece of music could be used to draw a Sacred Geometric Flower, by converting the bar lengths into centimetres and drawing the measurements on the page. The Golden Ratio and the Sacred Geometry behind the music gives the music its aesthetically pleasing symmetry, proportion and beauty. This began a study of the connection between music and mathematics. The musical intervals correspond with the multiplications of 9, as do the key signatures. Also, R.K. Owens studied how the music of the great composers, such as Beethoven, Chopin and Debussy, correspond with these aesthetically pleasing proportions. Geometric shapes, with the same ratios that occur in nature, can be drawn from the proportions of many of the masterpieces by the great composers. By the end of this book, you will know how to compose music that is structured according to the mathematics of the Golden Ratio, Vesica Piscis and Pi. This will make the music aesthetically proportional and symmetrical. A deeper study into the nature of the mathematics behind music may lead composers in the 21st century to write beautiful masterpieces for our own times.