From the first, Kepler had sought a rule relating the sizes of the orbits to the periods, but there was no slow series of steps towards this law as there had been towards the other two.
Mula sa unang, Kepler had sought ng isang patakaran na may kinalaman sa sukat ng orbits sa panahon, ngunit walang mabagal na serye ng mga hakbang tungo sa batas na ito bilang may had been patungo sa iba pang mga dalawang.