  We present and analyze results of the relativistic coupled-cluster
calculation of energies, hyperfine constants, and dipole matrix elements for
the $2s$, $2p_{1/2}$, and $2p_{3/2}$ states of Li atom. The calculations are
complete through the fourth order of many-body perturbation theory for energies
and through the fifth order for matrix elements and subsume certain chains of
diagrams in all orders. A nearly complete many-body calculation allows us to
draw conclusions on the convergence pattern of the coupled-cluster method. Our
analysis suggests that the high-order many-body contributions to energies and
matrix elements scale proportionally and provides a quantitative ground for
semi-empirical fits of {\em ab inito} matrix elements to experimental energies.
