 So it is in Day One that Galileo begins to discuss how to describe mathematically (or geometrically) the causes of the breaking of beams. But this requires a way to reconcile mathematical description with the physical constitution of material bodies. In this vein, Galileo rejects using finite atoms as a basis for physical discussion, since they are not representable by continuously divisible mathematical magnitudes. Instead, he treats matter as composed of infinitely many indivisible—which is to say, mathematical—points. This allows him to give mathematical accounts for various properties of matter. Among these are the density of matter, its coherence in material bodies, and the properties of the resisting media in which bodies move. The Second Day lays out the mathematical principles concerning how bodies break. Galileo does all this by reducing the problems of matter to problems of how a lever and a balance function, which renders them mathematically tractable via the law of the lever. He had begun this back in 1590, though this time he believes he is getting it right, showing mathematically how bits of matter solidify and stick together, and how they break into bits.