The Music of Numbers

“Mathematical science […] has these divisions: arithmetic, music, geometry, astronomy. Arithmetic is the discipline of absolute numerable quantity. Music is the discipline which treats of numbers in their relation to those things which are found in sound.” (Cassiodorus, cca. 6th century)

“Music is fashioned wholly in the likeness of numbers. […] Whatever is delightful in song is brought about by number. Sounds pass quickly away, but numbers, which are obscured by the corporeal element in sounds and movements, remain.“ (Anon, "Scholia Enchiriadis", cca. 900)

“Sound is generated by motion, since it belongs to the class of successive things. For this reason, while it exists when it is made, it no longer exists once it has been made. […] All music, especially mensurable music, is founded in perfection, combining in itself number and sound." (Jean de Muris, “Ars novae musicae”, 1319)

“The length of strings is not the direct and immediate reason behind the forms [ratios] of musical intervals, nor is their tension, nor their thickness, but rather, the ratios of the numbers of vibrations and impacts of air waves that go to strike our eardrum.” (Galileo Galilei, "Two New Sciences", 1638)

“We must distinguish carefully the ratios that our ears really perceive from those that the sounds expressed as numbers include.“ (Leonhard Euler, "Conjecture into the reasons for some dissonances generally heard in music", 1760)

“Music is like geometric figures and numbers, which are the universal forms of all possible objects of experience.” (Friedrich Nietzsche, “Birth of Tragedy”, 1872)

“In addition to this it [mathematics] provides its disciples with pleasures similar to painting and music. They admire the delicate harmony of the numbers and the forms; they marvel when a new discovery opens up to them an unexpected vista; and does the joy that they feel not have an aesthetic character even if the senses are not involved at all? […] For this reason I do not hesitate to say that mathematics deserves to be cultivated for its own sake, and I mean the theories which cannot be applied to physics just as much as the others.” (Henri Poincaré, 1897)

“Architecture is geometry made visible in the same sense that music is number made audible.” (Claude F Bragdon, “The Beautiful Necessity: Seven Essays on Theosophy and Architecture”, 1910)

“Through and through the world is infected with quantity: To talk sense is to talk quantities. It is not use saying the nation is large - How large? It is no use saying the radium is scarce - How scarce? You cannot evade quantity. You may fly to poetry and music, and quantity and number will face you in your rhythms and your octaves.” (Alfred N Whitehead, “The Aims of Education and Other Essays”, 1917)

“It is not surprising that the greatest mathematicians have again and again appealed to the arts in order to find some analogy to their own work. They have indeed found it in the most varied arts, in poetry, in painting, and in sculpture, although it would certainly seem that it is in music, the most abstract of all the arts, the art of number and of time, that we find the closest analogy.” (Havelock Ellis, “The Dance of Life”, 1923)

See also:
Music and Mathematics
Music and Mathematics II
Music and Mathematics III