of mathematical logic. For the latter the equation
r / t² = c (1 / r²)
is still an expression of Kepler’s observation. Not so for a logic which tries to keep in touch with concrete reality. For what meaning, relevant to the phenomenal universe as it manifests in space and time to physical perception, is there in stating – as the equation in this form does – that: the ratio between a planet’s distance from the sun and the square of its period is always proportional to the reciprocal value of the area lying inside its orbit?