The method of path coefficients is essentially a device for analysis or decomposition of a correlation coefficient under a structure of causal relationships among linearly related variables. This memorial note shows that Sir Ronald in 1918 had a clear notion that a correlation coefficient may consist of several 'factors,' each corresponding to a certain step or link in the chain of relationships between the two correlated variables. These 'factors' are precisely the path coefficients developed by Professor Wright simultaneously and independently. Fisher, however, apparently stopped there and failed to elaborate the basic concept into a comprehensive theory, while Wright, on the other hand, has consistently used it as the most important single tool to obtain in short order certain results in population genetics.