My question is:
why if I run some file with name aliases for example with content such as:

alias lsa="ls -a" 

directly:

$ ./aliases

it don't create the alias (may be only in script context).
But if I run it with command "source":

$ source aliases

it do the work? I mean after execution the alias "lsa" existing in context of command shell?
"man source" give: "No manual entry for source", and in google I just found that it runs Tcl, but why Tcl influence shell context and bush not?