AbstractWe derive the Wheeler‐de Witt equation for the scalar field of massm>0 in a Bianchi‐type I universe. We argue that classical trajectories become possible ath2⩽ αtp‐2,hbeing the mean Hubble value andtpthe Planck time. We feel justified to set the numerical constant α ≈︁ 1. We discuss this condition in geometrically invariant quantities and compare it with ⩽tp‐4. The proposed quantum boundary of classical trajectories represents a 3‐dimensional sphere in the 4‐space of the dynamical system. Equipartition of the initial energy over field (m