 If the said Galileus be at Rome or if you should know some other excellent mathematician-musician, I pray you to find out from him why, of all the sounds put together, only those which form the octave, the fifth, the third, and the sixth and their replicas are agreeable to the ear, and which of all the dissonances is the most disagreeable one and why. I have been told that the said Galilei knows this reason. (MC I: 603, translated in Mace 1970: 8)