  We discuss the foundation of the Trojan Horse Method (THM) within the
Inclusive Non-Elastic Breakup (INEB) theory. We demonstrate that the direct
part of the INEB cross section, which is of two-step character, becomes, in the
DWBA limit of the three-body theory with appropriate approximations and
redefinitions, similar in structure to the one-step THM cross section. We also
discuss the connection of the THM to the Surrogate Method (SM), which is a
genuine two-step process.
