  We use the Dyson-Wyld diagrammatic technique to analyze the infinite series
for the correlation functions of the velocity in the hydrodynamic turbulence.
We demonstrate the fundamental role played by the triple correlator of the
velocity in determining the entire statistics of the hydrodynamic turbulence.
All higher order correlation functions are expressed through the triple
correlator. This is shown through the suggested {\it{triangular}} resummation
of the infinite diagrammatic series for multi-point correlation functions. The
triangular resummation is the next logical step after the Dyson-Wyld {{\it
line}} resummation for the Green function and the double correlator. In
particular, it allows us to explain why the inverse cascade of the
two-dimensional hydrodynamic turbulence is close to Gaussian. Since the triple
correlator dictates the flux of energy $\varepsilon$ through the scales, we
support the Kolmogorov-1941 idea that $\varepsilon$ is one of the main
characteristics of hydrodynamic turbulence.
