  A formal relation between the GT part of the nuclear matrix elements
$M^0\nu}_{GT}$ of $0\nu\beta\beta$ decay and the closure matrix elements
$M^{2\nu}_{cl}$ of $2\nu\beta\beta$ decay is established. This relation is
based on the integral representation of these quantities in terms of their
dependence on the distance $r$ between the two nucleons undergoing
transformation. We also discuss the difficulties in determining the correct
values of the closure $2\nu\beta\beta$ decay matrix elements.
