Element's Compounds and Mixture's

I think ultimately all fields include classification. However, it is fascinating that everything whatever the shape , color, smell is :) all matter can be classified according to it's composition. Everything ~ !!! :) Actually, I recollected what my father always says. ' What you are made of never changes. ' (It's my father's way to say what kind of person that person is never changes. ) Although the phases the matter is in the ultimate composition doesn't change. For example, water, ice is totally different but they are all H2O. So this classification is an efficient and smart way to define things.