  We present a criterion for establishing Morita equivalence of monoidal
categories, and apply it to the categorical representation theory of reductive
groups $G$. We show that the "de Rham group algebra" $\mathcal D(G)$ (the
monoidal category of $\mathcal D$-modules on $G$) is Morita equivalent to the
universal Hecke category $\mathcal D(N \backslash G/N)$ and to its monodromic
variant $\widetilde{\mathcal D}(B \backslash G / B)$. In other words, de Rham
$G$-categories, i.e., module categories for $\mathcal D(G)$, satisfy a "highest
weight theorem" - they all appear in the decomposition of the universal
principal series representation $\mathcal D(G/N)$ or in twisted $\mathcal
D$-modules on the flag variety $\widetilde{\mathcal D}(G/B)$
