RE: Elisp - Store path only once

[Drew Adams]

> >(load 'g-eshell)
> >(load 'g-utils)
>
> (require 'something)

There are (at least) 3 functions you can use to load a list file: `require', 
`load-library', and `load'.

1. `require' loads the library (*.elc or *.el) only once,
   i.e., only if it hasn't yet been loaded.

2. `load-library' and `load' (also `load-file') load the
   library (*.elc or *.el) unconditionally, i.e., each time.

3. `load-library' looks for a library name in your `load-path'.
   `load' and `load-file expect a file name, not a library
   name, but `load' does search directories in `load-path',
   and `load' does try adding suffixes .elc and .el.

This is explained better than I've done here in the Emacs manual, node `Lisp 
Libraries' (ask Emacs).

https://www.gnu.org/software/emacs/manual/html_node/emacs/Lisp-Libraries.html