  The paper develops the theory of the ballistic SNS sandwich, in which the
Josephson effect exists without the proximity effect. The analysis essentially
revised the conclusions of previous works. The ballistic SNS sandwich is a
$\pi$ Josephson junction because its ground state corresponds not to zero
Josephson phase but to the phases $\pm \pi$. The analysis does not confirm
previous predictions on strong suppression of the supercurrent at temperatures
on the order or higher than the energy distance between Andreev levels. The
disagreement is explained by violations of the charge conservation in the
previous investigations. Other unusual properties of the ballistic SNS sandwich
are also discussed: the absence of the Josephson plasma mode localized at the
normal layer, the Meisner effect, and the Josephson vortex structure.
