We find necessary and sufficient conditions for the collapsibility
of a finite simplicial complex of arbitrary finite dimension. Our main result
states that any finite systolic simplicial complex of finite dimension,
collapses to a point. A simplicial complex is systolic if it is
simply connected, connected and locally
-large. Local
-largeness is a simple combinatorial condition defined in terms
of links in the complex. Our proof is based on the fact that any cycle in a systolic complex has a
van Kampen diagram of minimal area whose disk is itself systolic.