Fizicar Lee Smolin: "What is mass? We have some kind of intuition that it is a measure of "stuff" or "resistance to motion". But none of these captures it. An essential insight of Newton and contemporaries is that there is a conserved quantity of motion, which is momentum. Mass is nothing but the ratio between this quantity and velocity.

Thus to understand mass you have to understand momentum, and why it is conserved.[...]"

Ucio sam ucio fiziku po desetak casova nedeljno u skoli, ali niko mi nije objasnio osnovne pojmove ovako - ovde:

"Hooray for Lee Smolin's comment! I have thought this about physics pedagogy for decades without putting it into words so well. Physics is an intuitive, not a mathematical, science — one of the reasons why so many physicists do it so badly, because they too have been taught in this conventional way."

- Phil Anderson (dobitnik Nobelove nagrade za fiziku 1977)