“To give numerical values to this physical property [hardness], minerals are ranked along the Mohs scale, which is composed of 10 minerals that have been given arbitrary hardness values. As is indicated by the ranking in the scale, if a mineral is scratched by orthoclase but not by apatite, its Mohs hardness is between 5 and 6. In the determination procedure it is necessary to be certain that a scratch is actually made and not just a “chalk” mark that will rub off. If the species being tested is fine-grained, friable, or pulverulent, the test may only loosen grains without testing individual mineral surfaces; thus, certain textures or aggregate forms may hinder or prevent a true hardness determination.”
– Encyclopedia Britannica entry for “Mohs scale of mineral hardness”
Knowledge is not the creation of something new, but the exposition of that which is already present in a new light. The ritual of creation, be that through musical composition, or just thought in and of itself, can be understood as the process of gently scratching away the surface of our perceived reality to reveal that which lies beneath. This can be done using a number of approaches and whilst some may be brittle, leaving a trace of their process but making no impact, others are sharp and true, and are able to penetrate, leaving a lasting impression on the surface.