  We show that the series expansion of quantum field theory in the Feynman
diagrams can be explicitly mapped on the partition function of the simplicial
string theory -- the theory describing embeddings of the two--dimensional
simplicial complexes into the space--time of the field theory. The summation
over two--dimensional geometries in this theory is obtained from the summation
over the Feynman diagrams and the integration over the Schwinger parameters of
the propagators. We discuss the meaning of the obtained relation and derive the
one--dimensional analog of the simplicial theory on the example of the free
relativistic particle.
