  We prove a general principle satisfied by weakly precompact sets of
Lipschitz-free spaces. By this principle, certain infinite dimensional
phenomena in Lipschitz-free spaces over general metric spaces may be reduced to
the same phenomena in free spaces over their compact subsets. As easy
consequences we derive several new and some known results. The main new results
are: $\mathcal F(X)$ is weakly sequentially complete for every superreflexive
Banach space $X$, and $\mathcal F(M)$ has the Schur property and the
approximation property for every scattered complete metric space $M$.
