Rephrase paragraph describing how dependency resolution works
Clarify that pip is incrementally building up this information.
Clarify that pip has to download files, which contain the dependency information.
Hint at the fact that this is a recursive process.
@@ -11,10 +11,12 @@ When a user does a `pip install` (e.g. `pip install tea`), pip needs to work
out the package's dependencies (e.g. `spoon`, `hot-water`, `tea-leaves` etc.)
and what the versions of each of those dependencies it should install.
-pip does not have all the information it needs to work out the dependencies of
-the requested packages. Over the course of the dependency resolution process,
-pip needs to download distributions of the package, which can then provide
-the list of dependencies that the package requires.
+At the start of a `pip install` run, pip does not have all the dependency
+information of the requested packages. It needs to work out the dependencies
+of the requested packages, the dependencies of those dependencies, and so on.
+Over the course of the dependency resolution process, pip will need to download
+distribution files of the packages which are used to get the dependencies of a
+package.
## Backtracking
